Even if you believe Kahneman (I happen to), the $60k number is probably illusory for most Americans, since location is important. In NYC, perhaps the number is $95k; in rural Arkansas, perhaps it's $25k.
I'd love to see data on how the specific "ideal" income level varies by location.
I think NYC's cost of living is not that much higher than Tokyo's. However, as many pointed out in this thread, people care a lot about their income relative to their neighbors. So it's plausible that New Yorkers would require a much higher income to be content, compared to Tokyoites.
I'd love to see data on how the specific "ideal" income level varies by location.