In Mike's case, we're dealing with someone who probably can't really empathize with people still sulking because his idiot mother can't see that she made him feel like he doesn't matter any longer every time she cooed over Lizzie's every little move while shrugging off his attempts to call attention to his own accomplishments. Since he's not really good at understanding cause and effect and since he's dumb enough to think that if Lizzie were to go away, he'd be loved again, he gets into trouble he doesn't need and ends up with the reputation of "that dumb, mean angry kid who wants to murder his sister because he's selfish and dumb."
This makes him brother under the skin to fellow pinheaded brute Jeremy. Rather than blubber "How come he don't want me, man?" like Will did in that Fresh Prince about his gutless wonder absentee dad and not quite realize that his old man didn't have the guts to be a father, Jermy Wormy Jeremy came up with the brain fart of attacking anyone playing a harmonica in the insane belief that if they were to go away, his daddy would come back and love him. Since no one actually wants to be friends with an insane and deluded thug who wanted to pulverize someone who was no threat to him because he talked himself into thinking that she was mocking him for not having a dad, Elly's pious refusal to understand he should be left to rot meant that April was the only one who visited him while he was in his damned body cast.
The sad thing is that the Michaels and Jeremies of the world never quite outgrow the belief that people who have fun that make them feel bad aren't deliberately trying to hurt them. Mike probably still thinks that Lizzie asked to be born to ruin him because he believes that everyone is as animated by the need to roll over people as he is.