You can poison the routes within the BGP core to send traffic into a black hole. Basically, just tell everyone you have the best path, and they will send traffic to you.

There have been instances of this at the international level with adversary nations “accidentally” routing all traffic through them first. It can be done to a degree that it makes life difficult. They won’t be able to prevent you from finding a VPN that pops you out near a router that refuses the poisoned routes however- not without a global agreement at least.