I am in it strictly for the fun. The only challenge is to myself. That is why I do not log any caches found. I would do so if numbers were no longer posted. When I was in about 4th grade, the boys used to have contests in the rest room at school, to see who could pee the highest on the wall. I thought that was silly then, and I cannot see the difference between that and the people who visited a certain city and "bagged" (their term) 301 caches in 6 days (72 in one day). To me, that is just a blatant attempt to add to the numbers and not something that I personally would be proud of.
I do, however, always leave a note in the cache log itself thanking the person for hiding the cache, along with any other observations or comments about the hunt.
By the way, I have actually been a member since July 2001; I changed my nickname due to a conflict.