That doesn't take into account the hedonic treadmill.
The research is pretty clear - the difference in happiness and stress levels between making 300k and 400k as a family is pretty much nothing on average. The difference in happiness and stress levels between a family making 20k-40k is enormous.
Just because someone else would be happier with money currently in my pockets isn't a morally legitimate reason to take my money and give it to them, in my opinion, all else being equal.
I'm all for designing some kind of social contract, but I would like it to consider more than just relative wealth.
Also, in general I think it's a good idea to segment the population by net worth rather than income, not that I would advocate taking from those with high net worth either...
If money was originally distributed magically - by an amoral higher entity of some sort - would you be in favor of some democratically decided redistribution afterward to make it a little more fair? What if you had to decide the answer to that before you found out how much in lifetime earnings you'd be randomly assigned?
The unfortunate fact of our world is that, statistically, very few people escape their demographic and psychographic destiny. You can predict a 6 year old kids earnings as an adult fairly well from a mix of their birth geography, parents income, an iq test, and the marshmallow test. Some level of redistribution, that still rewards capitalist endeavors, makes sense in a society as unfair as ours.
I would argue that my 40% tax rate already qualifies as "some level of redistribution".
Like I said, I'd be happy to discuss some kind of social contract, but I get nervous about people saying "well he makes a lot of money, let's take it from him". That's too simplistic.
The research is pretty clear - the difference in happiness and stress levels between making 300k and 400k as a family is pretty much nothing on average. The difference in happiness and stress levels between a family making 20k-40k is enormous.