The moving to the new world involved taking on all sorts of new risks, but people still did it for non-economic reasons. Instead of religious freedom, perhaps others will be attracted by the prospect of starting new civilizations or escaping oppression?

The decision of some individuals to move from the british isles to N. America for religious reasons happened in a specific economic, geopolitical, and technological context. If the available vessels and navigation were poorer or more expensive, it would not have happened, and they would have done something else. You have to consider these things in their specific context.

So, given a strong enough desire for people to live "in space" or "on Mars" or "on Venus" combined with the technological and economic wherewithal to do it, people are going to try. Combine this with very wealthy national powers led by a class of engineer-technocrats with a demonstrated track record of implementing multiple decades long-term payoff projects (China) and the conclusion I come up with is that there is a significant chance that we will wind up with civilizations elsewhere in the solar system.

Also, the specific environment they're talking about in the article isn't anywhere close to the Mariana Trench. It's at about 1 atmosphere pressure. The most hostile thing about it would be constantly encountering sulphuric acid clouds. (This would also be a tremendous benefit, however.) Another important difference: The physics of building livable volume favors by far Venus human-aerostat altitudes over the Marianas Trench. Equipment for working "outside" in that specific Venus environment is something we already have a good idea about implementing inexpensively. The basic physics of the Marianas Trench makes doing the same down there orders of magnitude harder. Likewise, other basic physics around energy would preclude economically feasible agriculture in the trench, but indicates that it's quite doable at those altitudes on Venus.

A Venus colonist would probably sing songs praising PTFE. (One's already been written: "Polytetrafluoroethylene -- that's Teflon, you @ssholes!") Fortunately, we already know that one could condense fluorine directly out of the atmosphere of Venus with basically just energy as input.

I just can't imagine Venus specifically ever making it the top of anyone's list. Where's the plus to compensate for the many many minuses? It's certainly not the view.

Given enough energy, you can get water from the Venusian atmosphere. Granted, you basically can't have Venusian civilization without exploitation of space resources and having solved transportation costs to and from orbit, but water is not a hard barrier for a technological civilization.

Where's the plus to compensate for the many many minuses?

It may well become the cheapest place in the solar system to build human-habitable volumes. If you posit that there will be a solar system-spanning civilization in the first place, then physics and chemistry seems to suggest Venus has a lot of plusses in that particular context.

Granted, the only way that such a thing can come about could be properly termed sheer insanity. However, human history is practically made out of sheer insanity, chief of which can be called "nationalism". My money is on some power or powers at the scale of an industrialized nation-state eventually solving the problem of cheaply getting to and from orbit, motivated by the same sort of geopolitical insanity that motivated the Cold War. Given that, such a solar-system wide context of civilization will inevitably exist. All you need is one faction that makes it look like they might eventually establish such a civilization in their own image. Then competition will drive the rest. Look at it the other way: basically all such programs must 1) fail then acquire the aura of impossibility or insurmountability 2) forever remain out of the reach of private entities. It's entirely possible civilization may fall or some other circumstance would bring about those two conditions, but it's far from a certainty. Viewed in this way, completely earthbound humanity doesn't look like a stable configuration.