the "eggs in one basket" argument only makes sense if Martian colonization is itself just step 1 on a list of dozens of similarly-difficult leaps to get us to terraforming and interstellar colonization.

It's a very exciting, multi-generational project to think about. Though frankly I think we're going to get AGI + brain/computer interfaces + cloud mind uploads before we get martian terraforming; and dropping the bag-of-meat related requirements would make extraterrestrial colonization much easier.