[refulgentis]

First thought: I'm not the greatest at coming up with a stirring polemic justifying pushing out boundary science.

Next thought that come to my head is, how do I boundary-test this. ex. work my way backwards, what was the last collider worth building?

It's perfectly rational and intellectually honest to say "whichever one gave us something that got commercialized / helped people / etc."

As far as high-temperature superconductivity, I'm virtually certain if there was consensus a $XXB facility would concretely advance that, I assume it'd get funded.

I'm not certain, but I believe someone with more wherewithal / had skin in the game would argue that there's no reason to think this isn't that facility. (in that, advancing the boundary of physics tends to bring breakthroughs down the pipeline)

[gonzobonzo]

> what was the last collider worth building?...It's perfectly rational and intellectually honest to say "whichever one gave us something that got commercialized / helped people / etc."

It seems like the LHC wouldn't pass this test? In which case, continuing down the path wouldn't make sense under this criteria.

[refulgentis]

Right! :)

(the thing is, "continuing down the path" is a Not Even Wrong (in the Pauli sense) description of what's going on. It's a hopelessly confused. At least, I have given up hope: I wrote a quite detailed post, with both a TL;DR and longer, linking out to an approachable article, explaining this.)