If time travel exists, then Satoshi **_has to be_** a time traveller.

Either the future is horrible and bitcoin is necessary (situation # 1), or the future isn't horrible and bitcoin ruins some powerful people's stuff (situation # 2). In situation # 2, they would send a time traveller back to attack bitcoin early, and they can only succeed because they can try it an infinite number of times. Since that didn't happen, then only situation # 1 is possible.