Or maybe we just think that space travel being so expensive is as much a quality of there just not really being many reasons to do it and that it's reasonably likely that things can get much much cheaper pretty quickly if we actually wind up with a need for it. And that it's generally getting cheaper anyway.
I don't think anyone's claimed it is immediately practical, but a proof of concept for the thing would, in and of itself, be a threat to "the petrodollar" in that worldview.
And again, while there are problems, none of them are core issues with the basic concept the way ground solar's limits are. If the transmission gets solved in any of the several possible ways, the only remaining barrier is cost, and cost is NEVER a long term barrier.
...No, the problem with the cost of space travel is
not because there's 'just not really being many reasons to do it.'
It comes from something called the Tyranny of the Rocket Equation, and until we can get around that, instead of just make incremental efficiency improvements, things will always be bloody expensive.
On top of that, trillions of dollars of infrastructure in space, decades in the future, to take over
one of the functions that oil fills, which it already competes with coal, nuclear, and lesser power sources for, is
not a threat to the petrodollar. The foundation of the petrodollar is how
cheap it is to pump oil compared to other options, especially out of Saudi Arabia.
And something that needs billions of dollars of research, before the technology to do it even
exists, then trillions of dollars of infrastructure to make it,
is not a threat when the Saudis are entirely capable of pumping oil at 40$ a barrel, probably less.
You might as well run a pipeline to the sun, and use it for solar-thermal power. That's about how practical what you're proposing is right now, and any time in the next few decades.