"Duurrrr Imma man why should I pay for some ladies mammygram?"
That's the whole f**king point of what a risk pool is. That's the whole point of what INSURANCE is.
Women utilize more healthcare spending than men, so wouldn't it be fair to have separate risk pools, one for men and one for women?
How far do you want to take that? Old people use more than young people, so should there be risk pools for different age groups (and how many different age groups)? Or you can slice the population any number of other ways. The bigger the risk pool, the better it is for the overall population. Yes, this means that the healthy subsidize the sick. That's the way insurance works: those who don't use it subsidize those who do. It's the same with home insurance, car insurance, or any other kind.
As I understand it, the main objection that many people have is that they don't want to be forced to subsidize the health care of others. You can debate whether it's moral and/or legal to force everyone to participate in such a scheme; after much thinking about it, I've come to the conclusion that it's both, but I recognize that there are reasonable arguments against this. However,
if you accept that everybody is going to be covered, then putting everyone in the same pool is the best way to do it.