My boyfriend needs to sort his life out?

okay, my boyfriend is 20, and he is so immature.. he goes out and gets drunk every night, and he doesnt even have a job.. he talks about sorting his life out all the time but he never seems to do so. it seems like his top priority is getting pissed. and not only does he get drunk all the time, he gets really angry and violent when hes been drinking, so goes out and gets into fights and destroys other peoples property. i have spoken to his mother and she told me hes just a waste of space, but i dont want to leave him because i do love him and he would be a much better person if he just got a job and cut down on the drinking. and whenever he drinks, he argues with me about anything possible.. he still lives with his mum, but she was away for a week a couple weeks ago and he had a party and trashed the house, and hasnt been home since, just because he doesnt have the to take responsibility for his actions. he wants to go offshore, but the way hes going with his drinking, and getting into trouble with the police i dont see that happening, but i want the best for him and really want to help him change.. so any ideas on how i could do that? :/