The 80/20 rule applies. Up to about expert level you can put in 20% of the time and get 80% of the results. That's fun. Once you start having to study and do large amounts of preparation to get better and achieve results (and not for fun, but to the point of drudgery), you should either become a professional, or realize that you are spending a ton of time on a hobby you no longer enjoy ;)...
Compare this to, say, being a sketch artist. If you sketch for fun, great. If you want to become a graphic artist and make a living at it, great. If you want just draw the same basic stuff in a neverending cycle to slightly improve your ability, but you have no intention of ever making it your livelyhood...then perhaps you're lost your way and are wasting your time.
it is fun for me to play people within about 300-500 rating points of my rating. in non-tournament situations, it is fun no matter what the rating is, as long as im playing a chess variant (bughouse)`