Also if it was actually expensive enough, we'd simply be doomed. Economics can't be ignored. They're a proxy for how much we can accomplish.
The same goes for fossil fuel consumption. There's nothing economic about not using fossil fuels.
Understandably it's a compromise, but the first reaction shouldn't be "it costs too much, so don't do it". This attitude is the reason why nothing ends up getting done. I would much rather an uneconomic solution, than no solution at all, which seemingly is the status quo.
Perhaps it's become harder in our current society, but many great projects of man were economic folly.
To give one admittedly a little cliche example, landing on the moon never made any economic sense.
This is a statement of reality, not economic system. A society that decided to divert resources, today, to building a Dyson sphere on Alpha Centauri would fail, irrespective of economic system, because the goal demands more resources than it can sustainably divert.
Yes, that's my point. The worry about "economically feasible" in the ancestor comment is a question of what plans are realistic with unlimited motivation. It's not about economic systems holding us back.
If you want future viability, you can ask if there is a cheap way or an expensive way to get what you want. That's economics. It says nothing about what your goal is.
What you're arguing is a rational idea of economics that doesn't exist. Instead, we have this bastard version influenced by politics, which in practice, cares nothing of the key objectives which concern future viability.
Instead, we get this thing that demands infinite growth and consumption. That's modern economics and it's destroying us.
This is a stylised misinterpretation of economics.
It's because of economics we're in this mess in the first place.