Stop telling yourself that this struggle is worth it because maybe someday he'll have steady work and then he'll be a completely different person.

You're just propping this guy up and nursing his emotions while you shut up about your feelings and your offense at his shitty and insulting attitude. He doesn't appreciate you; he uses you as a punching bag to relieve his own shame instead of actually doing anything about it, like getting a job that may not be his first fucking choice.

If you aren't currently in therapy focusing on why you see it as your job to "fix" this jerk by letting him treat you like garbage, start ASAP.