Perhaps it would help if he worked with a psychologist that has experience with gifted adults. I agree that this has to come from him, and just asking you is a sign he wants to change. But he may need a bit of help.

Don't know if there are any where your brother lives, but I have just been recommended a psychologist to work with my DS15, who according to her web-site works with gifted adults. So I know this kind of help is out there. We haven't decided if we are going that route yet.