I used to play chess too! But I gave it up after a while because I lost interest, even though I had been completely addicted to it for about six months. When I eventually came back to chess, I wasn't as good as before, but I just kept playing anyway.
As for "what makes it worth it?" – just enjoy it! If you give up on something just because you're mediocre at first, you'll never get good at it.
I once heard a great quote: "If you only do what you can do, you will never be more than you are now.". It seems to me it was from "Kung Fu Panda" lol