Does it make sense to build the FCC, when it costs so much money and doesn't necessarily have enough energy to discover any new physics, at 10x the energy of the LHC?

Maybe it makes more sense to start working towards producing microscopic black holes in space, where results about quantum gravity can be gained [1].

[0] https://www.technologyreview.com/f/612766/cern-wants-to-buil...

[1] https://arxiv.org/abs/0908.1803 , Are Black Hole Starships Possible