Bill Gates once talked about money no longer having a utility for him. The utility of money goes away at a certain point when you accumulate too much and there is no longer something you cannot buy. The utility would be most efficient when applied to a better use such applied as the needy, perhaps in a UBI, or some other strategy, which would free up their time to do something more productive for society.
Unfortunately people don't like to help each other in many capitalist countries, and laws are designed to not be easily changed, resulting in a great majority of the population either not heard or reluctant to voice their opinions.
It took Bill a long time to get there too. But it's the same for any billionaire. They can't possibly spend their money, neither can their children or grandchildren so the only thing you can do with it is give it away. Be that to charity, good works, monuments to yourself (art museums, university buildings) or politicians and think-tanks in an attempt to bend the world to your will.
The money is just one scoreboard among billionaires and not great one. Murdoch would be far more self-impressed with his power he weilds through media than someone with an additionall couple of hundred million.
Gates is more interested in being the great philanthropist. It seems his scoreboard is how much positive effect on the world he can have. It sounds ideal and I don't like to be cynical about it.
Koch Brother(s), Soros also can't spend their money on more houses, cars and private jets. More money is only useful to get more power. Do you like the way either or both weild it? Do you think they should have a bigger say than you purely by virtue of cash rather than making a convincing case?
Unfortunately people don't like to help each other in many capitalist countries, and laws are designed to not be easily changed, resulting in a great majority of the population either not heard or reluctant to voice their opinions.