I think most of you don't even realize how short two weeks are, much less realize exactly how much sex they get within those two weeks. Unless you're a crazy nymphomaniac, in a two week period, you more than likely will get more entertainment out of the internet easily than sex. Parts hurt after a while if you do it too much consecutively. The worst that would happen using the internet too much consecutively is you'd get bored. But remember, the internet isn't just web browsing. It's shopping, chatting, gaming, video download/streaming. It offers a lot to do, and guaranteed that no matter how you're feeling, theres always something you'd find you'd like to do on the net. Sex, you're either in the mood for it or not. If you're not, well, that's just wasting time of your two weeks. And, again, unless you're a crazy nymphomaniac, everyones going to not utilize the full two weeks for sex. For the sake of the idea behind choosing between Net or Sex, they're comparing two forms of entertainment, and as for the best bang for your buck(hurr hurr,) the internet wins.
tl;dr version: Internet can appease more senses and moods for a lot longer than sex can.
That in no way counts as my answer.