I've seen some research on "relative income happiness" that suggest having poor(er) people nearby should increase happiness. Perhaps it doesn't apply if the income cap is to large...
Science is descriptive, not prescriptive. So no psych/social science research would ever claim that people are rational utility maximizing machines since they're descriptive by their very nature. And if people were rational utility maximizing machines such an effect would not be observed since happiness affected by social comparison is irrational. I don't understand how you came up with such a straw man.
I'm guessing sorisos is spot on with their last sentence. There's a big difference between being a millionaire surrounded by middle classers and being a lower classer surrounded by extreme poverty. Often times with happiness research there are caveats and ranges to keep in mind but the nuances tend to get lost in the headlines.