I assume you mean above and that's a very strong claim that I've found personally to be quite false.
Obviously this is referring to people in general and not you personally.
Couple huge notes here:
1. Overall life assessments improves; that is a part of happiness.
2. These numbers are 2009.. during the recession. They are way higher now almost certainly.
3. Needs to be COLA adjusted (linked article does that)
4. Is this pre-tax or post-tax?
5. I can't find the study itself, but I can't see how household composition wouldn't affect this number.
$130k single person in SF Bay Area might have well peaked on day-to-day happiness - you are generally making enough to not stress about breaking a budget.
At $130k living in the SF Bay Area with 2 young children, you are still going to need to budget, leading to heavy marital arguments about money that hurt day-to-day happiness. I would venture that $350k (pre-tax) is about the level where such a couple would peak by eliminating budget pressure.
It's a very American way of thinking, in which we fixate on being incredibly wealthy, instead of just moderately wealthy. Why else do Powerball sales skyrocket when the jackpot is hundreds of millions, instead of just millions? Statistically, your chances of winning were much better when it were in the mere millions, and now you have a much smaller chance, though to be very elite instead of just elite.