Am afraid its really hard to help those who do not want to be helped. Am sorry to hear about your son and how he's affecting the whole family.
Have you ever tried a little bit of tough love? 25 is too old to be playing games all day long. He really should be, at the very least, looking for a job. Perhaps you could hold a family meeting and see if you can all decide what would be the best way forward? If your son will not take part, then hold one with the rest of the family. And no, I do not think its unreasonable for you to insist he gets help.

Oh, any chance he is on drugs?