Invention is best fuelled by need. A motivation to colonise new worlds (either as a extinction safeguard as it's proposed in the article, or merely for economic exploitation) will drive the journey's price down. And a need for ways to stay in those new worlds will push technology so we don't die on Mars. And so on.

Nobody is going to spend billions to live in cities underwater. Simply, nobody wants to live underwater, or pay for it, or there is enough to be gained from that (we hurt the oceans enough already with fishing and others). And the eventual possible gain of maybe applicable useful knowledge is not enough to warrant the inversion.

It would be cool, though.