I agree with wearing seatbelts. I always wear mine. In fact, I hate the feeling of not wearing it. I like to be positioned securely in one spot when driving.

However, should it be illegal for someone with no dependants?

At a certain narrow point, what's the use of carving out a particular class of people from a general "use seatbelts in cars" law?

I suppose logically though someone with no dependents who signed some sort of waiver could be allowed, but it complicates enforcement measures quite a lot either way.