Thanks for the constructive comments. I am aware that my brother is technically an adult, but the fact of the matter is that he lives at home, and is only 24, and has demonstrated few adult behaviors to be treated as say equal to our dad who works overtime nearly every week and pays for everything.
I think the contributing to expenses might be a good idea, though it may call into question my younger brother's contribution, since he also lives at home (though he works). He did have a manager at one point, but maybe just not a good one? Even having an agent he'd have to respond to emails or calls, which I think he stopped doing.
I know it's humiliating for him to be treated like a teenager. That's part of why I want to help him! So dad won't resort to disciplining that he'd use on a child.
It is difficult for me to conceptualize how my brother does not see the need for him to grow up, and pay for himself. It feels as though he is avoiding reality in any way possible. If not for himself, at least he should respect his dad enough to know he must take on grown up responsibilities. I'm not asking for him to suddenly become a social butterfly! The most I can ask for is for him to get a job and start performing piano again, so at least he'll be doing something enjoyable with feedback from human beings, as opposed to playing a computer game for days, with no feedback from anyone.