It's not a matter of willing workers, it's a matter of funding. The problem is if you start demanding money in the form of taxes. I find it highly dubious that one rich person could fund such an endeavor all by himself; this kind of thing is a project of enormous magnitude, and just as with the Apollo missions, normally require the funding only possible with a very large nation-state, which gets that funding from taxes and has to answer to its voters.
If you can fund a Mars colonization mission all by yourself, then more power to you. But I just don't think it's possible, at least not any time soon. As a species, we haven't even managed to do any better than landing 3 men on our very nearby Moon for very short missions. We have zero experience in building and living in actual offworld habitats. It's never been done, not even in the one place where it's so close by that a rescue mission wouldn't be hard to do. The closest we've come is Biosphere II, a glass building in the Arizona desert, and that was a big failure.
