>>537898879
Getting better at instruments makes it more fun because you can play things you couldn't before. You effectively gain access to more complex and interesting songs.
Getting better at a videogame doesn't make it more fun in most cases because the highest level of play in a videogame is way more restrictive.

This is mainly a problem with skill based matchmaking. If you get good at a game without skill based matchmaking, TF2 for example, you can dominate matches singlehandedly if you get good enough. Getting more kills, dying less and winning more matches is your reward for getting better at the mechanics of the game.
With skill based matchmaking competitive games you are always in a hamsterwheel of constantly optimizing the fun out of the game and in turn the game puts against harder opponents which in turn means you need to optimise your play even further to win and have fun. Unless you care about your number on a leaderboard or go play on smurf accounts you will never feel the reward of getting better.

The fix is to just stop playing ranked. Stop caring about rank. Just go play normals and play whatever you feel like playing.