You fail to comprehend just how large space is. Almost all of space is well out of reach. There is zero reason to think we will ever be able to overcome the laws of relativity, which in turn mean we will never be able to reach the stars. I know, this negative comment makes you mad, but there is every reason to think it is the case.

A SciFi generation ship could maybe do that to the closest stars before it fails completely - but we have reason to think those stars will have any planet we can terraform. (ignoring the ethics if life exists - we don't have the technology to detect life on other planets)

Mars is the only planet that could potentially support human life. Even then the best parts are about as nice as Antarctica - not very nice. Which is to say a catastrophic failure of life support gives you seconds to get the backup [scuba type gear?] working as opposed to guaranteed death. Mars is a lot smaller than earth and has much less energy (less sun). Thus there isn't much potential there.

Everything else we can reasonably reach is much harder to work with than Mars.

Face it, earth is all we get: make it last.