Space is a hostile environment but not the most hostile people have ever entered. IMO, the most hostile environment we've entered is the deep oceans. When you get a couple miles down, the environment is far more dangerous than LEO or even the moon. A small leak on a manned spacecraft can be patched if found in time. A small leak on a deep diving submarine will have water coming in at such high pressure that it can cut steel. People can go outside of spacecraft if equipped with the proper spacesuit. Unless you believe the movie, "The Abyss" (good movie, BTW), humans are still limited to perhaps a couple thousand feet deep in the water. Space is hostile, but let's keep things in perspective.