So even if a very low percentage survive within underground settlements here it would be far better situation than being on Mars.

The difference is that on Mars, we're for the most part forced to build underground.

On Earth we have to choose to do so, and we haven't done enough of that so far.

Yet we still have infinitely more underground settlements on earth than we can conceivably have on Mars in any imaginable future...

That doesn't mean not trying to do something is a great idea.