is space travel worth the money?

I don't think so, it will lead to nothing of great value other than increase our knowledge of space travel, which, in the long run, will be little value to us.

Yes. The best answer was spoken long ago:

"We choose to go to the moon.

"We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win..."

'nuff said.

It's one of those things that isn't paying back the investment in the near term. But the human race must expand or stagnate. If we don't give up, in 150 years who knows what we'll be doing with space-based resources? We may be engaged in asteroid mining for minerals or water. We may be manufacturing in orbit, either to make pharmaceuticals we can't make in gravity, or to not pollute the Earth.

Europe could not have imagined in 1491 what wealth and freedom would come its way from some Genoese navigator's travels. And it took some centuries for most of the benefit to become recognizable.

Of course. Humans have an insatiable curiosity -- we must explore the unknown. Knowledge is valuable for its own sake.

Absolutely it is...

Man's future lies in the stars. If we turn our backs on it, we've doomed ourselves to same fate of the Earth. It's not going to last forever - whether we destroy it ourselves, or get smacked with a meteor - doesn't matter. If we can adapt to space, expand our presence, that's a way to ensure mankinds survival. We should take the steps now, and not wait for something bad to happen. "The time to dig the well is BEFORE you are thirsty"....

The "overhead" costs of space colonization seem large to us, but the eventual payoff is practically endless. We pay a fortune, certainly, but we get planets and asteroids and all their resources as the return on our investment. The break-even point might not come during the lifetimes of the original investors, but it will come, provided that the necessary work is are actually done (instead of merely talked about).

What's the alternative?

yes it is

Was Columbus' voyage worth the money? That's the thing about exploration - there's no way to be sure if it's worth it until you do it.