He was NOT the only one stealing from his father’s shop, though. And one’s gotta remember he started stealing from his dad because he was disillusioned with him, allowing all these strangers to come in, take advantage of his kindness, and rob him blind, all because he couldn’t conceive that not everyone was gonna be a friend (ironically, even young Jimmy knew better than that). And young Jimmy DID try to warn him about the guy coming in to rip him off, and that same scene implied that this is not the first thing this kind of thing has happened. Yes, we see young Jimmy stealing from the cash drawer in that scene, BUT we ALSO see his dad getting suckered out of some money. It’s worth noting that maybe Chuck doesn’t know (or wants to know) the whole story, given he blames Jimmy for everything, and always acts like he’s up to no good, even when THAT SAME GUY is literally looking after him while he’s sick.