So does the entire world, Bubba.
Professional -noun
1. a person who participates for gain or livelihood in an activity or field of endeavor often engaged in by amateurs.
2. those having a particular profession as a permanent career.
-adj
engaged in by persons receiving financial return.
Amateur -noun
1. a person who engages in a study, sport, or other activity for pleasure rather than for financial benefit or professional reasons.
2. those who have never competed for payment or for a monetary prize.
It's got nothing to do with skill. It has to do with working for a living. Professional writers do that. Amateurs do not. There is every skill level in both categories.
I might enjoy amateur books, but probably not. If they were any good, they could get them published and earn money on them. This is how it has always worked. Nothing has changed.