[dragonwriter]

Because, being over 85th percentile in intelligence, they would be more likely than average to realize that the marginal impact of income on experienced utility declines sharply the higher you go on the income distribution. (Especially if they’ve experienced life at a variety of income levels, including some near the 85th percentile.)

[sib]

Marginal impact decreases, but the absolute impact is still positive... And the marginal impact is still quite high at the 85th percentile of income because the income distribution is very skewed (the absolute dollar difference from 85th percentile to 99th percentile, where most HN / YC founders probably are on the intelligence scale, is probably much greater than the absolute dollar difference from 15th to 29th percentile, as an example).