Zubrin is a con artist.
He wants a repeat of the Apollo program to go to Mars and when its over- we'll have what we had when Apollo was over, some pictures, a few neat rocks.
He won't care cause he will be collecting the fat penson and all the other bennies that engineers of the Apollo generation got when they retired and he is jealous of.
The crash program to get to the moon was the wrong way to go about it. Von Braun knew it, tried to talk them out of it, but finally settled for "half a program is better than none".
Had he been listened to we would never of left the moon. Because it would have been too easy to get too to have bothered stopping. We would have had space stations, small, no bigger than Mier was but functional. One in orbit around Earth the other either in high lunar orbit or parked orbiting the Lagrange point between Earth and moon. The earth orbiting station would house a "space bus" to take people to the Lunar station where they could get a reuseable lunar lander and go to the surface. Everything perminent and/or reuseable in the system except the rockets used to lift stuff up. And even then, once all the components had been lifted up the big, expensive Saturns could be replaced by smaller, cheeper, mass produced ICBM based Atlas rockets.
If we had followed this approach, which might have taken a little longer, but in the long run cost less. Who knows what we could have done? One of the great 'could have beens' of human history.