There are two main reasons. First of all, as someone mentioned it in another thread here a few days ago, healthcare does not follow the rules of supply and demand, since people would pay anything for survival. You're never going to say that "ah this treatment is a bit overpriced; I think I'll get more value for my money if I'll just die instead". It's ridiculous. Second, there are various domains where the short term interests of various parties do not coincide with the long terms interests of everyone, hence regulation is needed. This is not political theory, it's game theory, it is nothing to do with personal opinion. It's a fact.
> Let's say that I have a genetic condition that is certain to kill me rapidly at age 30
You probably don't want to die then at 25 after not receiving a treatment after having car accident.
> Why should I be forced to pony up for other people's healthcare, too?
It's called compassion and it is a cornerstone of our civilization.
> The more insidious thing about universal healthcare is that it really screws over most minorities.
I don't know about that. I am not a doctor so I don't know whether such conditions really exist, but my gut feeling is that almost all of the stuff people get treated for are universal across various minorities.
> What if those who decide health coverage decide that heterozygous genetic condition X is covered...
I think this must be a fundamental, antagonistic difference between our world views. As a European conservative, I truly believe that no life is unnecessary, no life is wasted.
> ultimately, going to be a transfer of wealth from the poor (via inflation) to those who have the right genetic predisposition to conditions
Most of the things people get treated for have nothing or almost nothing to do with genetic conditions. There is no gene for suffering a car accident. While having unlucky genes could decrease the chances of survival, ultimately everyone can get cancer.