The first of these factors is their horrible selfishness and sense of entitlement. While it's true that Jean got to lecture John about how selfish a pig he was being, no one on Earth managed to force Mike to see that he was being a churlish little twerp about the whole thing; every time they tried, he just laid another freaking guilt trip because he simply couldn't be asked to see things from another person's point of view.
The reason for that is that is the insane belief Pattersons have that by doing so, he'll have to knuckle under to someone else's family politics and never be allowed to be right again. In his mind, having to accept the fact that his life has to change means that he loses and people will laugh at him and kick him in the face when he tries to get up off his knees. (Another example of this oh-so-Foobish belief that his is a life of brutal gladitorial combat is the way he treats Lizzie. As Mike sees it, she isn't a helpless child defending herself against pointless malice; in his mind, she spends her whole day plotting his ruin; this is why when questioned about his idiocy, the dumb bastard whines that she hurt his feelings. The sad thing is that Michael honestly believes this because the fact that any sort of objective look at the past would tend to indicate that the only way that she did so is by not taking abuse like she was supposed to.
This leads to the next annoying thing that keeps a Patterson from remembering things the way they actually happened: their inability to accept that their own behaviour could ever be inspired by malice, jealousy, spite and envy. While Mike is pretty good at noticing when other people are being jerks, he spends a lot of time and mental capital trying to avoid seeing that he too can be a royal pain in the arse as well as a greedy jerk and monster of vanity.
Finally, we have to contend with the fact that as a general rule, the Pattersons have no idea what's really going on around them owing to having their heads wedged up their arses. I can readily see a scenario in which Elly tried to explain to Michael that she didn't hate him but simply wanted to be treated like a person instead of a servant only to have Mike tune out because Mom was lecturing him about something stoopid. After all, most of why Mike's life sucks is because he's too dumb to know what's going on around him and too lazy to learn so his lack of brains and curiosity has to be most of why he got all bitchy.
What this means is that just as he shies away from admitting that he was a jealous little tool who treated his sister like shit because he was a sulking little globule of pus with an attitude that needed adjusting, he's not going to see himself as having been a sullen creepola who thought that Elly wanted to take away the childhood his real parent Network Television promised him. Either he's going to remember her as having spent even more time ranting about what she could have done with her life if she hadn't been burdened with selfish, greedy, ungrateful, chaos-loving children who hate her or he's going to remember himself as having been more supportive than he actually was. What he isn't going to see for a hill of beans is the fact that his life would have been a lot easier if he didn't think that people were trying to destroy him and laugh as they kicked him in the face.