After all, he sure isn't welcomed or loved at home. Not only does he have an asshole father with a hair-trigger temper touched off by the least thing, he's got a thin-skinned imbecile mother who cannot deal with conflict in a reasonable fashion. From the beginning of the strip in which she told Connie that Mike's being a normal kid trying to find his way in the world actually meant that he was a defiant monster who she couldn't love because he wanted to run her into the ground to her flat-out telling him when he was allowed to invade his own home and thus ruin her life, it's obvious that Elly saw Mike as a stranger that she couldn't be asked to tolerate until he became something she could identify with: an ignorant, anger-prone asshole who can't understand children and doesn't like having them around.
Searching for a home at school was futile too. From teachers who seemed to have the same lack of tolerance for his being a normal, average clod who only acted up because the people at home recoiled in horror when he got too close and an endless series of mean kids who exploited his pathetic need to belong to make a fool of him, we had the same Hell there only with different idiots expecting mindless obedience. The end result is that he expects humiliation and rejection because he hasn't the blindest idea how people actually behave because no one ever sat him down and talked to him; he's just winging it and basing his life on bad television because it's the only source of knowledge he was allowed.
About the only reinforcement he ever did get from his friends and relatives is angry nonsense about how, yes, the people who inconvenienced him are plotting against him so it's best to stay home and work for Elly and Elly alone. This is sort of a shame because when she and her lackeys aren't around to suck the fun out of things by never praising him, he can actually do good things.