What I see from the billionaires is a desire to undermine democratically elected governments, starving them of funding by cutting taxes, and making them dysfunctional by financing the campaigns of dysfunctional politicians. When the masses lose faith in democratically elected governments, the so-called "charitable" foundations swoop in to become the trusted providers of social services to the masses. The ultimate result is the elimination of democracy and the restoration of hereditary aristocracy, with the foundations ruling the world as undemocratic governments.
I would be more impressed if billionaires gave away 99% of their wealth to somewhere that is completely out of the control of themselves and their families.
The world's wealthiest people aren't looking to buy more stuff. There are only so many mansions and yachts you can buy before you'd had enough with that and get bored. For the purposes of buying stuff, wealth has diminishing returns. What they're looking for in accumulating unlimited wealth is to increase their power relative to everyone else, to perpetuate social inequality. Power is a kind of zero sum game, because if we all accumulate the same amount, we're still all equal.