Unpopular opinion time: his entire fucking life.
One of the things that makes Chris a hard watch is that it's very hard to say how much of him is nuture and how much is nature. Going in, Chris got dealt a pretty shitty hand. Being severely autistic can make things hard, after all. But a lot of Chris' more odious behavior can be directly laid at the feet of Barbara Chandler. All evidence is that every single time Bob tried to teach him responsibility, work ethics, or basic life lessons, Barb was right there to coddle the shit out of him and ensure none of it took.
Chris didn't have his needs met by mainstreaming; he got basically a dumbed down version of the same ciriculum everyone else got in his district and he never went on to any secondary education whatsoever. Because of this he never got the socialization or education he needed to help him cope with his issues. Barb enabled him and directly caused him to get worse. Barb taught him to hoard. Barb taught him to be completely dependent and failed to intervene with his bigger issues, letting them metastasize further. Bob unfortunately could only do so much, and had his own troubles in turn. He had no real friends. The tragedy with Chris is that Chris' combination of Autism and the utter failure of his socialization means that Chris inevitably burns out anyone who legitimately cares about him.
Now factor in his e-fame which he got through his own issues, and his more outrageous behavior circa the GAMe PLACe. An already deeply damaged individual became worse, and all the patterns Chris coined earlier have become more and more dangerous with time. Chris has increasingly been pushed into terrible things, and has taken more and more social and economic damage each time, allthewhile pushing away anyone who tries to help him. He belongs to the rare category of Lolcow who it's impossible to feel sorry for because he always fucks things up worse on his own and he appreciates nothing. No incident embodies this as much as the guard dog saga.
Perhaps most heartbreaking of all is that under the worst, there's signs that there's a better side to Chris. The part of him that donates to charity and encourages him to help out with events and try to be a good person at times. The stuff that Bob clearly tried to teach him and never really stuck. It's a chilling reminder that some people are their own worst enemy and will inevitably are brought low by their own flaws.