>The assumption is that it is somehow optimal for Bezos personally to extract maximal personal wealth constructing a pseudo-monopoly before exiting
I don't understand what you're saying. It's undeniable that Amazon revolutionized e-commerce and cloud computing. Otherwise nobody would be giving them money.
>the benefits accruing to a monopoly could theoretically just as easily be distributed to a collective as opposed to an individual, circumventing the billionaire issue
It does get distributed amongst a collective, and it's called equity. Theoretically, Amazon's first warehouse workers could have agreed to be paid in equity instead of cash, and then Bezos wouldn't have to take as much outside investment. If they had held on to this stock, they would easily be worth tens, if not hundreds of millions today. Obviously, this isn't practical in real life, so instead, this wealth got went to the investors that took on the risk.