omg...my"wanna be gang"friend.....advice!!!?

ok......so i have this friend and we have been friends for a really long time. I know about all of his family, except that his father past away. So about 2 weeks ago, his older brother got kicked out of the house because he was said to be in a gang, not a big one but a small one. The thing i that he got in trouble at school for doing some gang signs and stuuf. So now my friends thinks he should join his brothers gang. I told him he was crazy, but he said he wanted to show his brother he isnt a wimp and a loser. I am trying to stop him form making a stupid decision. And if i snitch, i'll lose a friend. I know all he wants his respect and his brother to be proud of him....but it aint worth him doing dat. He has a good reputation and is very smart. he has a future but he is going to waste it. I need very good advice and help. PLZZZZZZZ!!!!!oo i forgot to say i already told him..and all he does is push me away and says he doesnt care,"its his life"

Tell him the truth about why you don't want him to be in the gang and see what he says.