The way I read it is that both Dilbert and Wally are so desensitized that they cannot conceive of doing any hobby -- which is, by definition, something done for fun, not money. Whether or not this is Scott's view is open to debate.
Right now, I'm doing one of my useless hobbies: reading comics on the Internet. But it's not useless to Scott -- he gets paid by the advertisers.
To those getting upset about the bashing of their hobby, please remember:
This is comedy. One of the points of comedy is that EVERYONE is fair game, if you can make a joke about it. That means that, once in a while, you, or something/one you love, will be the target. Suck it up and have a laugh.
If you want to retaliate, retaliate in kind - make a joke, take the pi$$ out of Scott, or Dilbert, or Wally.
Don't just whinge, or complain that you don't understand.
BTW, my hobby is restoring old cars. I've had two MGs, a Triumph, and I currently drive an old Lotus. And I can take a joke.