Actually, I think you would be surprised how many people are actually into bondage today. I'd go as far as saying that 80% of people know about it, and will or have tried it as what it is (kinky; slightly sexual), and that about 25-40% of sexually active people in my generation are actually as crazy as we are all about it, and hold it as something almost essential to sexual practice.
The reason you believe that we're such a small and exclusive group is because most of us hold these feelings in a very personal and confidential regard.