Mars is very toxic. .5% of the soil is perchlorate. It's a megafund site.

What's more worrying for SpaceX is Musk's interview with Rogan. Whether you feel marijuana is something to be banned or not, SpaceX is an American Department of Defense contractor and the DOD has very strict rules of drugs, including 420, for its contractors. An investigation, I have been told, has begun and...he might have as bad happen for SpaceX (or worse) as what happened with Tesla. If he loses control of SpaceX, there won't be a private colonization of Mars by SpaceX.