Most of the artist on here usually fall in the humble category I think. Haven't seen too many artist who give their art threads "explosive names", at least from what I've seen.
Speaking from personal experience it's exactly as you put it. Beginners of any art form are not bound by the fears of producing "bad art" because they're oblivious to the reality of the world they're stepping into. They think all of their ideas are fresh, original and unique, that their art is so exceptionally awesome that they truly believe people will shower them with the praise they think their art deserves.
And then they get hit in the head by what I like to call real life. "This picture doesn't look that great... The shading is off... The head is too big compared to the rest of the body," or in my case since I'm a writer, "The pacing is all over the place... The writing is too choppy... This concept has been done a million times, can't you be a little more original?"
Suddenly their fantasy land falls apart and reality kicks in. They quickly realize that everything is not sunshine and rainbows, that they're nowhere near the great artist or writer they once believed themselves to be. And so from there, their love for drawing characters becomes never ending struggles to improve their work, and overtime, these struggles will have an draining effect on their confidence in some form. I guess you can say they become more jaded in a sense, and naturally, because their work has been criticized so much, most artist will feel as though their art is crappy and needs a lot more work.
I probably went a bit overboard with my response, but I think you get the point. Not gonna lie, I miss my younger days of coming up with stories to write. I legitimately thought everything I came up with was so cool and awesome, when in reality they were actually trash now that I look back on them lol.