I mean, there are huge mysteries in the neutrino sector, it's the one area of "physics beyond the standard model" where we know there is a something and not a nothing. All that other stuff about precision electroweak measurements, possible third flavor discoveries, and maybe just maybe just maybe the next collider can collect sparticles are just plain boring and a reason to leave the accelerator race to somebody who's willing to make unlimited capital investments to "catch up" to the west.