Going around the earth in 3 hours would require you to travel at 11 times the speed of sound, and that is without including the time it would take to accelerate or slow down.
The concorde flew at a maximum speed of twice the speed of sound. It would take the concorde 18h30m to fly around the world if it had enough fuel to do it.
Supersonic travel has some major issues. It takes a huge amount of energy to go that fast. Concorde could only cross the atlantic ocean, because it didn’t have enough fuel to cross the pacific. The other issue is sonic booms, which means you can’t fly supersonic over populated areas, like land.
Maglevs have the same issue as all other high-speed overland transport, it requires expensive infrastructure to be built the entire route. The faster you want to go, the flatter, smoother and more expensive the track will be to build.
Supersonic air is more plausible as it only requires a faster airplane. With wealth inequality, there are rich people who can afford their own supersonic plane, but an infrastructure project to build a global maglev network is far more expensive than that.