> despite what the media or anti-capitalists say, the top 1% are able to have the biggest impact
I think this argument misses, or even reinforces a core criticism about the concentration of wealth. The criticism is that so much and such disproportionate power should not be concentrated in the hands of one individual.
It's fundamentally undemocratic and a danger to society. In a democracy a broad-based group of citizens should be deciding where charitable resources are allocated. It's in aristocracies were a few wealthy control all the assets and make the decisions. Democracies were formed as a rejection of aristocracy, the U.S. in particular.
It's self-reinforcing: If the local 'aristocrat' funds a park, people are grateful because there were no other funds and now we have a park. But there are no other funds because we have a system that creates aristocrats and by concentrating wealth also creates the need for their charity, and instead of the citizens deciding democratically about their parks, the aristocrat decides.
Gates might be an enlightened despot but he's still a despot (in an exaggerated, metaphorical sense). We know what happens to nations and political systems that fall in love with enlightened despots.
> Somebody who donates a million (while a great contribution), will never have the impact that a billionaire can.
1,000 people who donate a million will have exactly the same impact as one who donates a billion and will be far more democratic. Far better: Each person makes an equal sacrifice (via a progressive taxation system) and we vote on how to spend the money.