Why can't we? Let's face it: everybody dies, no exceptions. Being born puts you under a death sentence, the only things open to debate are when and how. Now, a suicide mission, one where there's no chance of making a go of it, that'd be right out. But one where there'd be the equipment and supplies to stand a reasonable chance of making a go of it (eg. having the stuff to build greenhouses for food and oxygen, and basic supplies for long enough to be able to build and bootstrap what we need), I'd jump at that chance (though in my case age and physical condition would probably disqualify me). My view on it is that if it doesn't work out then it didn't work out, and at least I went out having taken my swing at it. If you try there's always a chance you'll fail, but you'll never do if you never try.
You think nobody died opening the American West? You think nobody joined a wagon train until there was no chance Indians or bandits or breakdowns or weather could leave everyone dead or stranded with no hope of rescue? Hah.