Stardom isn’t normal. It’s familiar, even commonplace—ever-present not only in the realm of actors, singers, and other pop entertainers, but also in the overlapping circles of athletes, politicians, tech “visionaries,” and ambiguously skilled celebrities-as-celebrities whom Americans love to ogle, aggrandize, belittle, and resent. The impulse to idolize is as old as the gods, of course. Jesus was a superstar some time before Andrew Lloyd Webber came around.
While incompetence is a common condition of amateurism, it is not a requirement of it. Plenty of non-professionals in all of the arts are well-skilled, in many cases expertly trained and perhaps even seasoned in their disciplines. The only absolute prerequisite for amateur status is passion. You have to want very badly to sing or play the piano or draw or tap-dance, if you'll do it with no prospect of recognition or compensation. And if very badly is also the way you do the thing, your passion has to run deep.