> believe the answer is that the USA will be better able to outcompete those countries that do have them

Based on what? The US already outcompetes these other countries in business success and average citizen income. What countries don’t have billionaires that are competitive?

> History has shown time and again that massive inequality is a huge barrier to maximizing the productivity of all of a society's members.

History has literally never shown this. This is the first time we’ve had massive inequality while still having a solid middle class. The jury is still out on whether the instability of the past was just because of excessive poverty and no upward mobility or because wealthy people were there.