If the fittest shall survive, Why do the unfit still live?

Answer 1

Because that's not how it works. "Survival of the fittest" is a concept popularized by persons other than Darwin. For purposes of evolutionary selection, 'fitness' is simply the ability to produce offspring that live to maturity; it is not purely an inherent characteristic but a rough measure of how well those traits promote survival in a given set of circumstances. What is useful in one environment may be detrimental elsewhere; some traits also have trade-offs, for example attracting a mate vs. attracting predators.

The disparity is not between 'fit' and 'unfit' - it is the degree to which greater 'fitness' allows one to produce more offspring, *and* pass on those traits to its descendants. Generally the difference is not dramatically apparent in a single generation, but adds up over time. In other words, 'fit' and 'unfit' are not absolute categories but relative concepts on a broad continuum.

Very few individuals are clearly 'unfit' - and they usually don't survive to reproduce. Only in a supportive society (such as ours) does such a thing take place.

Answer 2

because society helps the unfit

Answer 3

good health insurance

Answer 4

So the fit can make fun of us.