Don't think that because people have worse problems that you aren't at least entitled to ask for advice for your own, OP. Sometimes peoples problems are caused by their own attitudes towards others, but they will never see it.
Your best bet is to try and get your parents to see your brother as a problem, and put the pressure on him to try and sort himself out. You could do this by turning on some power-devouring equipment during the night so the powerbill skyrockets, then mention that it is probably due to your brother using power during the night. You could also get rid of some food in the middle of the night and your parents might assume your brother or his GF ate it, and that's another expense. Play dirty! and remember that money is the deciding factor in just about everything that involves it in some way.