If you're frustrated then you should quit. When it starts to feel like a chore you're paying to work a job when you should be paying to enjoy something.

If you really want to keep playing you might have to avoid pigeon-holing yourself. If BLM is the only thing you like and you want to work on only that you'll lead yourself to frustration if you can't meet your goal. You could try leveling some other jobs to make a bit of money here and there.

While I think there are a lot of way to play and have fun and feel that the game has a ton of redeeming value, if you hate the way leveling works it's probably just not for you. Not every game is for everyone.