Is this even true? It might violate a trademark, but I don't think it would violate copyright law unless it was a copy of an existing picture.
For example, if you rent a movie, you can watch it with your family. Nobody is going to sue you for distributing the movie with 5 people in your room. That's pure nonsense. Same with music, books, etc.
If you try to play the movie in an establishment with dozens of people, then it can become a problem, because you're essentially a theater now.
I'm not a lawyer so I don't know what the law is on selling fan art on a convention or even privately commissioned fan artwork. But things aren't as draconian as people assume it is.