I'm inclined to believe the premise. Tax is just better at equalising. But, I do respect the Gates for their philanthropy towards health, especially, women's reproductive health during a time US political toxicity removed a huge amount of aid due to the anti abortionists power in domestic politics.
Bill Gates was a destructive businessman. His philanthropy is tied up in his "power" world view. The way the press fawns over his every word is nauseating and a part of this power dynamic. We worship the rich.
I think having got to a certain place with a big caveat, what he and Melinda Gates are choosing to do with the pile of money, is better than what other people (Bezos, Musk) are doing with the money. Even Bezos' ex-wife is doing better things with her share of the money.
The caveat is that I am told, the Gates often require you to use Microsoft IT to do whatever thing you're doing.