> particle physicists should focus on developing new technologies that could bring colliders back in a reasonable price range and hold off digging more tunnels

People keeping saying this, but we haven't been permitted to dig a single new tunnel since 1983. Multiple proposed colliders have been shot down, with the US's attempt defunded in the middle of construction. The LHC doesn't even have its own tunnel; it was put in the 1983 tunnel to save money. To save more money, the LHC is going to run for another 20 years, so any future collider's tunnel won't be dug until 2040 at the earliest.

That is a nearly 60 year gap between new tunnels, which I find incredibly depressing. What I find almost incomprehensible, though, is that the people who successfully argued to defund earlier proposed colliders now argue to defund the next one on the basis that our field is progressing slowly! I wonder why that is?