So, you can't make a non-porn site with tons of traffic pay...but you expect to build a porn site that makes money?
I will humbly point out that porn clicks are some of the least valuable clicks in the industry. Sites like YouPorn, with huge traffic, aren't exactly making a killing (they aren't going broke, either, as far as I know, but a handful of these sites are in the top 50 on the Internet...there are non-porn sites that are dramatically less popular that are making a lot more money). If you expect an easy road to that level of popularity and traffic, and expect your porn site revenues to be respectable very quickly and without a lot of work, I suspect you'll be disappointed.
That said, there have now been a few reasonable exits for adult Internet businesses in the past two years. Before that, it would have been foolish for someone who wanted to be really rich to start a porn site...unless they planned to go "all in" in the industry and become a major player for years to come. It's still far less likely for a porn startup to be acquired than a non-porn startup, and this is reflected in the hesitance of VCs in investing in adult startups (it just doesn't happen, and it's not because the majority of VCs would have ethical issues with such investments). And, going public is pretty much impossible for a porn business, so the VCs that are looking for a huge score are simply not going to be interested. Of course, if you're bootstrapping, you don't care about VCs or exits.
All of that said, about six or seven years ago I did some infrastructure work for one of the top-tier porn empire builders (I won't name names, but at the time, his network was very likely the second largest). He paid on time, was a joy to work with, and had very serious hardware running his sites. He had no problem spending hundreds of thousands of dollars for expenses (his bandwidth bill the month I worked for him was $86k, for example, and that was after he'd negotiated a new deal that dropped those expenses by tens of thousands per month), so his revenue was obviously respectable. But, he'd worked hard to build it--it took several years to reach that level. He worked directly with the content providers who were creating new branded content exclusively for his network, he had his own porn ad network (because he had 30 or so brands to promote, he could buy in large blocks, and also could barter with friendly competitors), and he was extremely focused (which I think might be lacking for you, if you're thinking of porn as a stopgap measure just until your "real" project gets going).
I know several people who have had some level of success building small projects specifically for revenue generation, and I don't think you have to go the porn route to get there. Since you're obviously uncomfortable with that path...why not choose something else that provides recurring revenue without a huge investment of time? Widgets, iPhone apps, Flash games, etc. all are pretty small projects that can produce a few hundred a month in revenue.
Or, perhaps you should be seeking investors for your "real" project. That's how most successful tech businesses were started, you know?