> What's the worst thing a monopolist can do? Charge unfairly large prices.
It's not so much about Rockefeller being a monopolist as it is about him being a private citizen with truly enormous economic power, while being zealously devoted to a simple cause, and having the ability to rationalize away all doubts. These are worrying personality traits that facilitate doing great damage.
In the case of Rockefeller, these personality traits led to constructive outcomes, but the point I was trying to make toward the end was that it seemed a chance event that he would use his power for the philanthropic projects that he chose.
Here's a hypothetical: what if, for instance, Rockefeller had supported eugenics rather than medical science? How would that have turned out?