There's a pretty substantial difference between "living on the other side of the ocean" and "living in a submarine", which is probably what life on Mars would be like given foreseeable technology. It's not just fear of the unknown. It's the sheer practical matter that life on Mars (if possible) will be extremely difficult, and the only obvious benefit is that you can say "hey look, I'm on Mars!"
Hell, you can simulate life on Mars by signing up for a career in deep sea diving. Actually, deep sea diving is probably a million times easier since you can pretty easily get parts from the surface.
I should have posted the full Bruce Sterling quote:
I'll believe in people settling Mars at about the
same time I see people setting the Gobi Desert.
The Gobi Desert is about a thousand times
as hospitable as Mars and five hundred times
cheaper and easier to reach. Nobody ever
writes "Gobi Desert Opera" because, well,
it's just kind of plonkingly obvious that there's
no good reason to go there and live. It's ugly,
it's inhospitable and there's no way to
make it pay. Mars is just the same, really.
We just romanticize it because it's so hard to reach.
On the other hand, there might really be some
way to make living in the Gobi Desert pay.
And if that were the case, and you really
had communities making a nice cheerful
go of daily life on arid, freezing, barren rock
and sand, then a cultural transfer to Mars
might make a certain sense.
If there were a society with enough technical
power to terraform Mars, they would
certainly do it. On the other hand.
by the time they got around to messing with Mars,
they would have been using all that power
to transform _themselves_. So by the time
they got there and started rebuilding the
Martian atmosphere wholesale, they wouldn't
look or act a whole lot like Hollywood extras.