People who feel like impostors will often "play it safe" by not even attempting a creative project, out of a self-limiting belief of being incompetent.
Actor Emma Watson commented about its impact for her:
“It’s almost like the better I do, the more my feeling of inadequacy actually increases, because I’m just going, Any moment, someone’s going to find out I’m a total fraud, and that I don’t deserve any of what I’ve achieved.