Because USA is where people make most money if they are elite level.....in any profession.
Probably helps that the world currency is pretty much the dollar but only americans can emit this currency 😁
Personally I took lessons with high level players but they will teach you a high level style of play (constant attack/loop).
At this point I aim to a more relaxed passive style where I can just have fun and not destroy every single ball with all my power like pros do.
Not to mention many high level players end up with injuries so probably not a style worth chasing.
here Eugene lost to Cifuentes from Argentina so his current ittf ranking should be around 90 - 120
here's another match you could watch....Alto (Cifuentes doubles partner) with a ittf ranking 181 against an amateur player.
In this case you can see Alto clearly taking it easy against maybe a US-2300 guy.