The once and future US manned space program did much to attract winners to the US. When that died, like Project Orion, due to a lack of political will, the winners stayed home or went elsewhere.
Some countries send us their criminals, while current and past Admins like to import musselmen. Any value, any cultuire, except ours is acceptable.
Most things in which we used to lead are now done elsewhere; we’ve lost our exceptionalism, and the upper crusts of the Third World countries know it.