Actually, I think that was the joke all along: the hypocrisy of Walter constantly telling Donnie he is “out of his element“ when Walter is the one who is clearly delusional and unhinged.

I see what you’re saying Dude - he is not actually out of his element. But here we are; it’s Shabbos. Er…uhhh…I mean,

…Dude, let’s not forget, let’s NOT forget, that Donny also could be pretty clueless at times, i.e. “phone’s ringing, Dude”, or “His name is Lebowski? That’s your name, Dude!”, as if he was dropping some helpful knowledge.

Donnie definitely got more abuse than he deserved, but I think a big part of that was just his timid demeanor meant he would take it and Walter knew that. The Dude pushes back against Walter’s bullying all the time (you’re not wrong, Walter, you’re just an asshole; sooner or later, you’re gonna have to face the fact that you’re a goddamn moron, fuck you, Walter and fuck the tournament, etc) but Donny doesn’t, so Walter is generally meaner to him because he knows he can get away with it, even though we all know deep down, Walter cared deeply about him.