Your friend is smart. Understand his niche: old ugly motherfuckers, most likely divorced and angry, who fly to a certain country once or twice a year to be in paradise surrounded by beautiful young hookers. They feel young and vibrant again for those few weeks a year, and the rest of the year all they can do is think about going back. During that time they look at photos from that place, watch videos from that place, get teary-eyed thinking about their favorite hookers they half in love with in that place, they make hooker slideshows on youtube with Travelling Wilburies or Journey as the background music, they post on forums talking about p4p (pay for play, as they like to call it) and how to go about it strategically so you get the best girls at the cheapest prices with the least hassle, etc. It's an obsessive niche. I don't mind outing it because I'm sick of porn affiliate programs stiffing me so I've ditched adult entirely. But if I wanted to make a porn membership site, it would be surrounding a sex travel niche like this. Bangkok and Pattaya, Thailand are a bit played out, and there are a million sites about them. But there are other destinations with the same obsessive p4p culture.
Anyway, your friend came up with a better idea than you. Stop being a crybaby and make some more fucking sites, this time without paying $10,000 for the domain without having a solid business plan. I have free hosted sites on blogger that make me $1000 a month each. Because I invested no money in any domain, if after a certain amount of effort I got no results then I just deleted the site and tried something else. It's a lot easier to get stuck on a bad idea when you paid $10,000 to try it out. You have to be willing to abandon your projects when you're starting out. I don't recommend you use blogger, but an $8 domain should do the trick.