JC,
After we played together last, at Bandon Trails if you recall, I told you that your swing is much better than what your handicap suggested. I am not sure how you took it- it was meant as encouragement- but I have absolutely no doubt that you can be a solid mid-single digit player.
Actually, the key to becoming better is 180* from JohnK's quip. The more tournament play you put under your belt, the better you will become, assuming of course that your sense of pride will require that you prepare for the tournaments.
The other thing that might hold you back is the number of courses you play as rater, some for the first time, others occasionally. Not only does it likely affect your handicap, but it trains a focus that is different than that which leads to minimizing your score. When your mind is trained on picking out all the features and subtleties of a golf course, it is likely not focused on getting the ball into the hole in the fewest strokes.
Having said all this, I think there is a Peter Principle in all things including golf. I have a friend at Reynolds Plantation who did very well in manufacturing and sold his company at a relatively young age to a bigger outfit that just had to have it. He is an excellent athlete, lettered in varsity baksetball and baseball in high school; a terror in neighborhood softball and basketball games. He loves golf, works very hard at it, but can not lower his handicap much below 10. But even this guy has not reached his PP. I know this because when I've played with him and he asks me for help, I can get him to hit the ball better. Unfortunately, as soon as he goes on his own, he reverts to his old habits. And as you know, in golf, the difference between an acceptable shot and a horrendous one is often extremely small.
I do think we tend to reach a comfort level with a range of scores and our game might acclimate to it. One of my biggest fears about moving up to the short tees is that pretty soon my scoring would adapt and I'd be shooting the same scores from the shorties as I did from further back. A lot is in the mind and these days mine is not doing to well, probably around an 18.