Side-Effects of Healthcare

The other day, discussion over lunch turned towards the popular subject of Jews. How brilliant they are. How shrewd they are. How most of the Nobel prizes in basic sciences have gone to Jews and so on. We also got to hear the natural selection arguments -- that says that the centuries of persecution of Jews has made sure that only the best of the best of them survive. That has resulted in a small but extremely purified gene pool among the present Jewish population.

This naturally led us to the undying arguments about the fundamental effect of improved healthcare on human race. In short, healthcare's main function is to support the life of the diseased. In general, it also means that it supports those lives who would otherwise have been lost because their bodies are too weak to survive. That means, healthcare is defying the basic law of natural selection which results in the survival of the fittest. Healthcare will result in the survival of the unfit too. We being in the healthcare industry can say how much rejoicing there is in the industry because the world population is growing older and there's a huge growing market for healthcare products and services. How, then, do we expect the human race to become stronger in the long run?

I think the argument is strong. But I have the following doubts:
Is it possible to defy the law of natural selection in the long run? If these bad guys whom healthcare is making live longer are finally going to meet their grievous end a few hundred generations down the line, the point of natural selection is reaffirmed, albiet a bit late. What big deal is that in the billion year long Earth calender? Natural selection seems to prove its point whether it sets in or not. What I mean is if these bad guys do manage to survive till doomsday, then they are the fit ones. It's just the 'fitness' gets redefined. Whoever said that fitness is just physical fitness?
The above point apart, is there any harm done by letting these unfit individuals exist by the side of the fit ones? OK, there will be cross breeding resulting in poorer gene pool. But there will still be some to carry the pure genes. How does that reduce the chances of the survival of the entire species is hard to comprehend.

Anyway, just to give a corny philosophical close to the discussion, it's said that death is nature's way to give way to new things. Had there been no death, there would have been no need to evolve, no need to innovate, no need to improve. No species would have seen the best of itself had there been no death. Death is after all not such a bad thing. If the average human life is about 75 years, we anyway lose 1/75 of the world population every year. That must be a huge number! Then why does death shock us so much? Why do we care so much to avoid it? These are innocent comtemplative questions, not condescending ones. Which means, death does shock me. And I care to avoid it at all cost for myself and my dear ones. But I don't know why!