Japan has doujinshi culture: self published comics. Twice a year there is an event called Comiket where the main attraction is the release of new doujinshi. A lot of professional creators get their start by making doujinshi.

While some doujinshi violate copyrights, publishers look the other way because they understand that this is the source of their talent pool.

The closest thing we have to this in the west is fan fiction. We could never have a Comiket type event for fanfiction, because the corporates would not hesitate to squash it.