What is more likely to revolutionise physics - spending $20bn on an incremental increase in collider energies, on spending $20bn funding a new generation of PhDs and postdocs exploring quantum gravity fundamentals?
At this point practical HEP shows every signs of being a boondoggle. There are plenty of hard theoretical questions that haven't been answered, but with a few exceptions they're outside of the mainstream. Research into them has been actively discouraged, except at a few locations.
Physics doesn't need more hardware, it needs more ideas - more intellectual diversity, and more creativity.