> The fact that our relatively small population supports the GDP it does is wild.
Yes and no. It is very impressive what humans can do and the US is a remarkable country for managing to achieve what they have. On the other hand, if we're talking GDP it is basically just a trendline [0] of whether you let people better their own lives or not.
The main reason for US success on the GDP front is that the median administrator chooses to make people fail and the US does the best job of resisting that tendency. To me the mystery is less why the US succeeds but more why polities are so committed to failing. It isn't even like there is a political ideology that genuinely wants to make it hard to do business [1]. It mostly happens by accident, foolishness and ignorance.
[0] https://www.grumpy-economist.com/p/the-cost-of-regulation - see the figure, note the logarithmic axis
[1] I suppose the environmentalists, maybe.