I worry about the other things that might keep us from expanding into space, such
as dwindling resources, dwindling money, the increasing ignorance and selfishness of
humans in general, a global nuclear or biological war, a totalitarian regime taking over
much of the world and keeping the rest of civilization fighting it for survival, and so
forth.

I do not expect everyone to leave Earth and live in other parts of the galaxy. I do
expect and hope that enough humans get off this planet so that if something does
go wrong on Earth, we will at least have a few pockets of humanity left to carry on
the species and society.

I predict the first ones to leave Earth will not be some NASA-funded lunar or Mars
colony, but some other type of private group disatisfied with society and its
treatment towards them.

Or the Chinese.

As for needing to get out of the Sol system before the Sun goes giant red bloated
star of death, just because it is several billion years in the future does not mean
we should just loll around until we start noticing how hot things are getting and the
oceans are evaporting into giant piles of steam before we do something about it.
If we leave Earth and the Sol system in the next century, we won't have to worry
about things here 2 to 5 billion years from now.

That is the other thing I worry about: A lack of ambition and dreams of greater things,
and way too much focus on transient, too local things.