Another argument made is that it simply cannot be done at this moment in time. If we could put a man on the moon in the 1960’s, we will find a way to put a man on Mars, especially given that we’ve already successfully landed multiple rovers and landers on the planet. Yes, it is difficult and there are risks, but it can be done if we want to do it. The fact it is a challenge makes it worthwhile.
We also do not believe finding a team to go on a one way trip would be a problem, as long as it is well planned, and there is a strategy in place to keep them well supplied and safe. While a lot of people could not imagine why you would want to give up your life on Earth to live on a desolate planet, there are many people out there who not only crave adventure and the unknown, even knowing they are unlikely to return, but would also gladly want to go down in history as the first pioneers to colonise another planet.