I have a theory on why Phil is the way he is. So put your tinfoil hats on and activate your almonds because this is one detailed theory. So here it is:
My theory is that Phil has sort of a multiple personality issue in which his current personality was created to hide his weak personality. When he talked about his past as a kid, it sounded like he was a pushover, a weird introvert, had mental issues, and a cuck. So, first off he stated that he stalked a girl back in high school because he was "obsessed" with her, which is definitely a sign of mental issues or a really awkward kid that never had real friends or a female interaction. He also explains how he took a "cocktail of medications" back in high school that made him do weird things like the stalking. Now if he was taking a "cocktail of medications" then that means Phil must have had some mental issues or was on the spectrum, therefore Phil is hiding something about his health.
Next, Phil is a clear case of being a spoiled only child based on his bs wolverine story, his story about his mom buying an N64, and how he saw his full-grown parents as morons and he, a 10-year-old child, was a freaking prodigy. Which makes me think when he went to school, he pushed his "I am always right because my parents said I was the best" spoiled mentality but the other kids, being kids, laughed at him and picked on him for being a goober. After years of being bullied, he broke down to an introvert with little to no friends. Once he entered middle school, he was a broken child who couldn’t handle human interaction. That is why when the hot Latina grinded up on him, he freaked out when the boyfriend wanted to kick his ass. But I think something did happen and he got his ass kicked or the Latina was pulling a "schmucks for dinner" situation and grinded on him to see his autistic reaction while her friends laughed.
Either way, when he got to high school, he broke down even further and became mentally unstable, that is when his parents put him on a "cocktail of medications" to calm the unstable high school Phil. He probably broke down further when he got cucked by that girl at that prom/homecoming when she went with him but left him for another guy when they got to the dance. So, knowing he could not have friends he just focused on his studies hoping people would like him if he was smart and thus was just booked smart. He then became valedictorian at a school that probably had kids who didn't care about grades, basically, he was the smartest turd in a giant pile of shit.
Once, he went to college he started to stabilize a bit and realize he might need to change from being a loser to a chad. So, Phil started "working out" thinking that if he was buff he could be a chad because clearly being book smart didn't help. However, book smart Phil didn't know how to work out properly and never saw any large gains but maybe lost some weight and instead of lifting 5 pounds he now lifted 15 pounds which in his weak ego-mind was him being buff.
(Quick Note: His idea of muscle memory is completely wrong. Phil thinks muscle memory (MM) is that if you worked out and then stop working out for 10 years that you keep some of that muscle. No, if you stop working out for 10 years your muscle will shrink to the point of being average or in the case of Phil below average. The real definition of MM is when you work out properly your muscle motor skills retain the pattern of lifting weights, so if you stop working out then work out again your muscles will remember the motor skill to lift the weight properly thus boosting your muscle gain because you are doing the movements properly. In some cases, in which you stop working out for only a few weeks, you can bounce back to your previous max weight lift quicker because your body retains that memory that it liked working out. But if you stop working out for 10 years you are not going to have that quick gain, he might remember the lift technique but since his muscles are weak as fuck and the gap for his muscles to remember the feel of working out is so vast that essentially it will be like if he started working out for the first time and take forever to get gains.
TL; DR Phil was never buff and knows nothing about working out or the definitions for any of the words in the weight lifting community. Source: Took exercise physiology classes and have been weight lifting since I was 15 years old.)
So, in the real world, Phil was a socially/mentally unstable awkward person and no matter how much he studied and worked out improperly, he was not liked by other normal humans. But he realized the only place he could be a "chad" was at the arcade because clearly, Phil was that kid that played alone in his room with all the vidya games his parents bought him. So when he went to his first arcade he probably saw some normal kids playing street fighter, but since he did nothing but play games he was above average than most at the arcade and won matches. This gave birth to "chad" Phil who thought he was hot shit because he beat some average kids in street fighter, thus his fondness and obsession of loving street fighter. When he started to do tournaments, "chad" Phil realized he wasn't the best as there were other kids as good or better than his ass. But "chad" Phil couldn't let his high of "being the best" die, so he started to act like a dick to show "dominance". Over time, he was probably mocked and laughed at for trying to be a cool guy that was good at fighting games, thus he took that hate and decided to embrace this negativity, thus embracing his dark side. I know Phil likes to mention that story on why he named himself DarkSydePhil but I think he called himself that to show that he wasn't a pushover and that people should fear the dark side of himself. Therefore, he created DarkSydePhil to shield himself from the cruel world that bullied him for so many years. Of course, Phil probably knew that DSP would only work in the FGC and not the real world, thus why IRL he was still a loser. You can see this when he created that troll website talking shit about the FGC because on that website it was all about the FGC so that persona fit well in it. But when he was confronted in real-life situations, like when that street fighter player (I think Viscant or whatever that guy was named) accepted his IRL fight, Phil freaked out thinking that the DSP persona would be useful in that situation. But, it just showed that the DSP persona had flaws because Phils real pussy self still came out the cracks when the situation involved his real physical body to be in danger. That is why he tried to weasel out the fight by telling the guy to sign paperwork and faking the fight to be a draw, but the other player being a real human laughed at him and told him to fuck off with his bs excuse.
When he started to upload videos to YouTube, he used his DSP persona because that was the most confident version of himself, and since it was the internet he could be Mr. Badass without actually physically confronting a person. When his channel boomed, Phil thought that this DSP persona was beloved by many and that is what people wanted so he kept up his DSP persona. When people asked him if his DSP persona was fake, Phil freaked out because he didn’t want his fans to know his real pussy self, so he lied and told everyone that DSP was his real self and that he is a badass that takes no shit. (Quick Note: Recently Phil has stated that his old YouTube self was a fake version of himself that exaggerated things, even though for years he stated that his YouTube self is how he really is in real life. This supports my theory that the DSP persona was a shield.)
At this point Phil realized that his DSP persona was attracting girls, thus he lured in PandaLee with that persona. Well, it worked and he had a freshly new 18-year-old girl by his side all because of his DSP persona. Now most YouTubers would have kept their GF/BF a secret because it was no one’s business to know who they are as they don’t want their significant others to be bothered by online people. But not Phil, he had to show the world his new 18-year-old GF because his real pussy self-needed this win, basically to give a weak middle finger to the world that he wasn’t a loser and that he can get pussy. Instead, everyone hated her and trolled her ass, which then Phil blamed the trolls and his fans for not understanding why he had to reveal his GF. Well the second GF he got, Phil finally learned from his first GF reveal...nope, he revealed her knowing very well the consequences. This time though Phil tried to hide his GF but when the escort saga started and when people were saying he didn’t have a GF, of course, real-life pussy Phil couldn’t handle the ridicule from children/teenagers and thus caved in under pressure and revealed his GF. Even to the point of challenging the internet/kiwifarms (never challenge the internet/kiwifarms, it’s always a losing bet) that they can’t dox her.
When people watched Phil back in the day (including myself) we thought his personality in the videos was an act, but when he started to say it wasn’t an act then that is when people were slowly turning on him. See people only like assholes when they know its an act, like AVGN, Francis, DrDisrespect, AngryJoe, and so on. This is because in real life they are normal people that respect their fans and aren’t psychopaths (Boogie has fallen but back in the day people liked him as a person, now he just sucks as a human). So those youtubers/streamers can retain the audience because their fans know that their online personas are just for entertainment purposes only. Phil on the other hand embraced his DSP persona 24/7 because he thought people liked an asshole all the time even during Q&As, meet-ups, and moderating his videos. However, that pushed away people because no one likes an actor that is an actual villain, thus normal people couldn’t relate to DSP since that guy was just an asshat. This led to his channel to slowly die, detractors to be born, kiwifarms talking about him, and the illegal restreams. I guarantee you if Phil would have said his DSP persona was just an act and was genuinely nice to people, he wouldn’t have the issues he has today. The only reason Phil kept saying his DSP persona was his real self was that it made him feel better about himself since deep down he is a shell of a man who can’t handle the real world.
You can see this weak version of Phil come out through the cracks of his DSP mask when trolls push his buttons. For instance, the balding comments get him all the time, to the point he makes exceptional excuses like it was his moms’ fault for combing it that way or that his headphones are parting his hair (which some nice people on this site proved to be bs as headphones don’t do that). Also, when people mention his glasses, he states he doesn’t need them and it's only for driving, its like he is ashamed to wear them. I bet he hates those glasses because when he got them in high school he got furthered laughed at and by that time Phil was already broken so he stopped wearing them because he didn’t want to get bullied more. This is further supported when Rambo mentions that a cop told him why he wasn’t wearing his glasses when driving, clearly Phil was embarrassed to wear them even though Rambo himself wore glasses so why be ashamed if your friend wears them too. Simple answer, Phil avoids anything that makes him more of a loser. We can also see his pussy self come out when trolls talk about his wife, family, his finances, his weight, his proficiency in vidya games, and so on.
In conclusion, Phil is a broken man who gave birth to the DSP persona to shield himself from the real world. Unfortunately, his weak pussy real self still shows through those cracks on his DSP mask which can be seen from his alcoholism, constant lying, insulting, wanting validation of his successes like his 10-year shit playing online, gluttony, greed, begging for pity, and acceptance from the world that doesn’t want him.