As long as you follow the community rules and abide by the licenses that the creators selected. Time and time again I see in local groups people selling others works. It’s not cool to steal an STL and sell it if the creators license forbids it.

With that said, if you created and designed all your own, go for it!

I do not, but as an avid printer of a bunch of years now, I would absolutely purchase some stuff if I saw it at a flea market.

One of the dispensaries I visit from time to time has some sick dragons with gradient filaments on display. Sadly they weren’t for sale. So, I’ll make my own.