It's easy to make an argument that this is negligible, and far more experienced people can make this argument quite well. The money should trickle down, but I think it might help if we had more wealth to trickle down in the first place.
Many contribute to charities do this to avoid taxes, I've had first-hand experience with this type of "charity". The people who actually want to help tend to want to pay taxes, in my experience.
So who is really donating to the charity ultimately?
I'm not saying these benevolent people don't exist, it's just that if you distributed all of Bezos's wealth to each person individually it would only be ~1000 per person once or less, a meager stimulus package. How is that wealth going to trickle down fast enough to have any meaningful effect? Money tends to accumulate towards those who value it the most, but perhaps more wealth could be accumulated if more of it could flow through the system without being trapped only in the wealthy hands.
It could be a win-win, or a win-lose, but it's not a lose for the rich at all if they can now select from a much larger workforce--charity money rarely reaches those that need it most. Just like how many homeless on the street aren't in a desperate situation, and those that are probably can't monopolize those good street corners.
Ultimately there's a feedback loop between supply and demand--any incentive to increase either helps the majority.