I find it interesting, at least in DEN, that you walk into the lounges and they have ads everywhere for the Club card - why would anyone be interested in a Club card if they are already in the lounge?
(yes, there are other ways to get into - but hopefully you get my point)

I pay for the club card as I found myself rarely using the 1-day passes (I find other value in UA chase cards) as going into a club, using a pass, for a 90min layover wasnt worth it - and the longer layovers, in places like ORD rarely would accept them....now if I have a few hours, I keep busy by bouncing from club to club.....

but, to the OP - I also have wondered if anyone pays for membership out-right.... not using OPM, not writing it off as a business expense, not via CC, not using points (I need to look into paying for my Club CC with points)......