When it comes down to space travel it is really all dangerous. But the question is whether it is too dangerous. Not for the purpose it serves. As human beings we have a natural desire to explore. It is what makes us who we are and it is how we advance as a society. Many technological advances in our own lifetime are in many thanks to the people who risk their lives in the vacuum of space. Many advances have been made recently and the history books are re-written everyday by what we learn in space. It wasn't too long ago that we wondered what would happen if a black hole would enter our galaxy, It was only recently that we discovered that our galaxy actually circles a black hole.
There have been many speculations about Mars over the years, from our older civilizations having originally come from the planet, to the possibility that Mars has once and may in the future support life. Canals corroded by water flow have been discovered and it is theorized that Mars may have once looked much like our own planet. It is one thing to look at things through the looking glass, but it is another to discover in person. It is important for us to put a person on Mars for the only reason that has ever made any sense. Knowledge.
There was a time when space travel itself was thought as too dangerous, but we had to try, Walking on the moon was thought as too dangerous, but we had to try. A free floating space walk was thought too dangerous, but we had to try. Is a trip to Mars too Dangerous? Who care! WE HAVE TO TRY. It's in our nature, in our blood and it is what makes us who we are.
There will be a time when all of mankind looks back at landing on Mars as being no big deal. On this day we might be living on another planet, or traveling in personal space ships through the galaxy from star to star. As we advance we learn more about safety and the right way to go forth and discover. In the mean time, if we stopped doing things because it "might be too dangerous," then we would still be sitting in cave painting stick figures on the wall. We wouldn't be human if we didn't leave the cave and check out what the universe has to offer.