They can migrate to the American southwest and do agricultural labor, competing with the illegal immigrants doing jobs that "Americans just won't do". They can migrate to the distant outskirts of high productivity cities (e.g. NY, SF), then commute in and provide domestic labor to high productivity individuals. There is plenty of opportunity out there; if there weren't then people from around the world wouldn't be desperately attempting to enter the US.
Hundreds of millions of Indians, Chinese and others engage in internal migration, moving themselves to where the jobs are. Americans could too.
This is just not a fix that Silicon Valley can do; if a man doesn't want to fix himself, then Peter Thiel can't build an app to do it for him.