it's actually quite ok to EXPECT a 25 year old person to be self sufficient and living on their own. as it is, he's still getting treated like he's a 14 year old - lives rent free, at home, and has mom drive him around. so you could see this "transfer of residence" as a good and positive thing. a rite of passage, vaulted into adulthood.
he'll survive. you may not like his choices, in fact you may HATE them, but they will be HIS CHOICES. if he wants to punch holes in walls, he can do so to HIS walls. if he ends up in jail, his problem. if he loses a job, his problem.
if between now and the time he leaves, he becomes violent and threatens you IN YOUR HOME, call the police. don't give him special treatment, hold him to the same rules and standards and laws that the rest of us abide by.