This is the thing I find most fascinating about Phil.
With most lolcows, it's pretty obvious why they are they way they are when you look at their upbringings/early lives: generally, they tend to come from broken/fundamentally messed up homes, be born with serious mental/physical abnormalities, and/or grow up under enabler parents who never properly disciplined them, but this doesn't seem to be the case with Phil. He grew up in your typical middle-class suburban household, and while his parents probably spoiled him a bit as a kid they didn't seem to be Bossmanjack-tier enablers; they were willing to punish him when he crashed his car, so it's not as if they were letting him run hog wild doing whatever he wanted without consequence.
Which just begs the question of how exactly Phil got to be such a massive egotistical asshole. It's true that some people are just born-dicks, but Phil is extreme even by born-dick standards, and he seems to have been that way right out of the gate. You go back 20 years to tophaters.com and Evo and Phil is exactly the same obnoxious jackass he is today, snorts and all. Hell even as far back as age 13, with the Wolverine story, the guy was an entitled prick.
I don't think we really know that much about Phil's childhood. If nothing else, his mom coddled him to the point of brushing his hair until he was well into his teens.