[FrustratedMonky]

But, that is still giving a happiness score.

If the society/culture you are living within. Is well off, but swamped with cravings that it could be better. Then you are less happy.

This study isn't trying to measure how 'materially well off you are', it is happiness. So if you are un-satisfied even with your big house, and un-happy, that still says something.

[dyauspitr]

It’s also a culture score. Objectively we should all be very unhappy because we’re not all billionaires and can’t do whatever we want but culture tempers at what point you’re content.

[jltsiren]

The kind of a person who thinks they would be substantially happier as a billionaire would probably be unhappy as a billionaire. You get used to what you have, but there is always more wealth / status / power / influence to be had.