Oh yes, very difficult, very expensive, but suppose the next generation antibiotics could only be found there? (As an example of a compelling reason I just made up right here on the spot)...
What the moon landings ought to have taught us (and indeed did at the time) was that where there’s a will, there’s a way. A compelling reason to Mars ought to get mankind there in some way.
Unfortunately, we seem to have lost much of that national will since the long, cold slide into liberalism started in the 1960s.
As a retiring executive from a skunk works entity remarked, “If you can dream it, we have already done it”!
I would not be surprised if the reason the space shuttle was scrapped is that we do have the means of space transport that will be kept top secret for years to come.