Personally:
I hope that I will always be able to play this game casually on my own schedule, but tournament competition no longer appeals to me. As someone that has been rated over 950 for several years now, I do not play anywhere near as much as I once did. Discgolf to me has just about as much significance as going bowling, or playing a game of spades. It is a fun activity, but for me, it's all about the people and new experiences. Playing against opponents that spend 5+ hours a day, 7 days a week on this game is part of what ruined it for me. My hand-eye coordination and the ranking system force me to compete against the top level of amateurs, but their unbalanced lifestyle is not something that I would ever want to emulate. For their sakes, I hope that they are magnificent at this one game, because they are missing out on so much more by devoting so much of themselves to it. Family, friends, career, religion, travel, and growth through new experiences are all much too important to me to ever want to dump so much of myself into just one thing. So I'll pass.
Generally:
I also think that by attaching the word "quit" to the subject, you are getting a lot of false bravado responses. The simple fact of the matter is that it is completely normal for people to become interested in something, learn it to the point of near mastery, then eventually move on to the next thing out of boredom. The hunger for the next new challenge is part of what makes us humans great.