Love for Sale?

So here's what I've never understood: Match.com has this offer where, if you spend a fruitless six months on the site, they'll give you another six months free. That makes no sense to me. If you've spent more than $100 on a web site that promises to help you find the love of your life, and you're unsuccessful after six months, seems to me you'd want your money back, not another six months free.