We haven't colonized the oceans yet, a place where very exotic life abounds.

How can we argue about colonizing remote worlds ?

How can a governement be in favor of its citizens escaping from Earth ?
I'm sure only a minority of space interested folks believe that can be sold to the public.

What happened 40 years ago was flag and footsteps, exploration, and technological and engineering prowess. That could be sold to the public!

It wasn't about science (though science made it possible for 2 astronauts to spend more than 22 hours outide on the Moon, traveling 35 km, rather than just one astronaut stepping outside for a few minutes as was planned for a while in 1963), it certainly wasn't about saving mankind in case of a global scale disaster on Earth. It also isn't about colonizing other worlds because ours is no good anymore.

But it can be about showing what can be done if we want to and are willing to make the effort.
It must be short term (in order to captivate the public), it must be accessible (in order not to force too much spending) and it needs to be relevant to the public.

The Apollo program was sustainable for more than a decade, thanks to the efforts of thousands, the commitment, the deadline, the room for mistakes, the inertia from the enormity of the accomplishment.

Going to Mars is so different with our current technology. It would only involve 4 or 6 astronauts every three years. What is currently sold for its manned visit is so far from the reasonable way of testing humans and systems and the time and money it will take for it, I don't see this happening until I'm gone.