If you own and he rents than you selling and moving would cost you a LOT for little gain ... in all seriousness if he's a renter and a pothead he'll eventually move, you may just have to wait him out.

Don't do anything dumb ... I'd hate to see you in jail (and lose your 2A rights) over something like this.

Talk to your other neighbors ... if you can get a bunch of them angry about this guy maybe you can get a petition together and maybe get management to get rid of him for you.