What to do about lazy brother?

I have a brother, 26 years of age, who I feel is leeching off my parents. He still lives with my parents. When he was 18 he went away to college and my parents took out a loan for him. They are still paying on this loan. My brother has totaled at least 4 of their cars. He has gone to many colleges and either used financial aid or my parents have paid for him and he never finished a semester or he received unsatisfactory grades. Two years ago he got a DUI - wrecked my parents car. My parents paid the court cost, bailed him out of jail and paid his attorney fees. My brother has now gained significant amount of weight - at 5"4" he is 260lbs. My parents now pay for a local gym membership for him. My brother has a vision problem that has progressively gotten worse. Since he has no job he has no insurance to help with this medical problem. My parents are scrapping to buy medical insurance for him. On top of all this my parents are retired and on a fixed income. I have had several arguments with my parents about their continued support of my lazy brother. My parents tell me to leave them alone. They feel they have to help him until he gets on his feet. I feel he has become a financial drain on them. I refuse to help my brother in any way. I feel my parents have not prepared him for life, they have given him everything and he has never had to work for anything. The more I talk to my parents and express my concern the angrier my parents get and tell me to stay out of it. Talking to my brother is just as disappointing, he doesn't even try to help himself. It's almost like why should he do anything if my parents will do it for him. I have other siblings and they don't get involved which I think is crazy. What if anything can I do?