That seems a bit reductive; I don't even know that you're "wrong", but there are a lot of factors that might have led to the United States' success. We have a lot of natural resources and a lot of our land is readily habitable.

Yes, the US also has relatively liberal economics [1], and maybe that's why the US has done well, but I think there are too many confounding variables to conclude it's purely because of economic liberalism.

[1] I mean liberal in the academic sense, not as a synonym for Democrat.