I didn't say the best times in the US were 50-60 years ago.

I said that historians would consider the start of the decline was 1969 or 1973 or similar.

Declines start in the second derivative -- progress is positive, but the rate of progress increases is decreasing. It takes a long time with a negative second derivative to make the first derivative negative, but the decline started when the second derivative turned negative. And the second derivative made an obvious turn around 1970.

And it's also measured relatively. It 1969 it was obviously way better to be an American than a European or a Korean or Japanese. Even than a Russian, although it wasn't as obvious at the time. In 2026 I'd rather be born in Europe than the US if I don't get to choose to be born to rich white parents.