You’ve put the cart about a mile before the horse here. Wealthy people display the characteristics that made them wealthy.
This is your own unsupported assumption. You point out that the study does not definitively prove which way causation goes, and then you pick the other side.
Generally, being autonomous is a choice, like starting a business, and starting that business could lead to more wealth. Wealthy people tend to be self starters, this attitude made them wealthy, it wasn’t the wealth that made them autonomous.
These are all assumptions, and some are just flat out wrong. You seriously think working ‘autonomously’ is ‘generally a choice’ for most people? That is, you think most workers actually have a choice to do something like start their own business? Wealthy people are often wealthy because they had capital to work with in the first place. It’s a lot easier to start a business when you know you’ll be able to feed your family tomorrow even if you fail.
You’re drawing the conclusion that wealthy people are fundamentally different (more willing to use leisure time actively because they’re just ‘go-getters) from average working people. That seems extremely specious given what we know about social mobility.