If Nick's disappearance has anything to do with this "secret life" of his, I think it's more likely to be connected to the Wet Spot than to his connections with the AFF Thursday night group.
The club is a three minute drive from work. If they have an ATM that would make a lot of sense why he would use his secret pay pal account card and also why LE would not show the picture or video of the place he withdrew the money!
Whatever happened after that nobody knows but we know his car ended up at the condos in Federal Way. Maybe he went home with somebody, went to sleep and the next thing he knew LE was after him?