Only if you think the point of money is consumption or saving for future consumption and not dry powder for class mobility (investments / housing / schooling for children / social signaling).
No it doesn't - what if you had a trillion dollars. You could spend the money on saving the penguins, or developing a Linux distribution that's just the way you like it, or clean up the ocean, or start a Manhattan project for breakthrough battery tech, or teach kids math in Africa, or convert a large number of people to your religion, or fund the arts, or fund an expedition to Mars, or any number of things.
Human needs are infinite. There will always, always be more good and worthwhile things to buy.
According to whom? The research I've seen on this confirms Bernoulli's intuition that happiness scales with the logarithm of income.
Sure, the logarithm is slowly varying in the limit, but that seems like a very unusual definition of both "beyond some amount" and "absolute amount stops mattering."
The logarithmic decay could be more about more and more people hitting their satisfaction level, than about what the wealth can purchase. In other words, very few people actually want to be billionaires.
> Beyond some amount the absolute amount of money really stops to matter
At national monetary scales, sure, because more spending would be inflationary thereby decreasing one’s spending power. So call it a trillion dollars or so. Not a practically relevant cap.
AFAICT, the most expensive yacht is the History Supreme, which is only 100ft but is built from, among other things, 10 tons of gold and platinum. $4.8B.