I mean, empirical evidence exists as it is now. We can look at the most wealthy countries and determine if they were the most impoverished ones a generation ago. We can look at the most impoverished nations and look if they were the wealthiest ones a generation ago.
If we look multigenerationally, the longest-living nations are still the nations that can maintain a high quality of life the longest. It is frankly nonsensical to say that nations fall because they reached a high point; of course they can only fall if they have someplace to fall from.