I'd expect them to screw up much more often than they succeed. But if 25 people take a risk and found a company and 1 of them succeeds, that one company might employ 1000 people. The 24 failures may be worth it. That's leaving aside whatever useful services the company provides.

~20% of the world population of foreign-born people lives in the US. It's difficult to think that's unrelated to the fact that the US produces a disproportionate amount of global innovation.