I have long characterized my performance at a lot of hobbies (chess, scrabble, clarinet and saxophone, hockey, skiing and snowboarding, trivia) in the following way, I am better than any casual player, but I am the worst amongst the people I participate in the activity with.
I always thought this made me a dilettante.
I play chess well enough from for having read several books and own several chess clocks, but I typically lose against anyone else who takes the game seriously. I continued with clarinet and saxophone well into grad school (far beyond when most people dropped music) but I was always the least skillful musician in any group I performed in. I played roller hockey every weekend in grad school, which made me passable, but I was typically the worst player who didn't quit playing. I ski and snowboard comfortable (more or less) on the hardest terrain available (from lifts anyway) at most mountains, even the unmarked ones, but I am almost always the least skilled one on those trails. I recently started playing scrabble on facebook, and helped spread that viral addiction. I always thought I was much better than most casual players who are impressed by the use of words like Qat and Xi and Jo and Aa, but I find these days I lose most games I play, where even getting a Bingo in a game (use all 7 letters for 50 bonus points) isn't enough.
Today I started wondering if this was somehow endogenous.
How much depends on how I push myself into the groups I associate with, and how much is merely outlook. Maybe everyone feels this way.