Let's say your tax rate is 50% and your taxable income is $1,000,000, so you'll owe $500,000 in taxes. If you donate $100,000 to charity as a "tax write-off", now your taxable income is only $900,000 and you'll only owe $450,000 in taxes, but you lost $100,000 to save that $50,000. At the end of the day, you'll have $50,000 less than if you didn't donate anything.
Before anyone starts with "but what if it drops you into a lower tax bracket!": a) that's not how marginal taxes work, and b) the top tax bracket starts at $518,400 in the US in 2021, and I'm pretty sure Bezos made many times that amount.
"It's a tax write-off" doesn't make sense mathematically. It's not a thing. There's not a plausible way where giving away money can improve your bottom line over not giving it away without having tax rates above 100%, which we don't have.
From 2014 to 2018 his wealth grew by 99B, and he paid under 1B in taxes. Would love a sub 1% effective tax rate.
And a stock you own going up in value is not income. It does not trigger tax liability. If he doesn't sell shares right now, he is simply deferring tax liability to a future date. He is not cheating the tax man. His tax rate is not less than 1%.
Jerry: How is it a write off?
Kramer: They just write it off.
Jerry: Write it off of what?
Kramer: They just write it off!
Jerry: You don't even know what a write off is, do you?
Kramer: No. Do you?
Jerry: No I don't!!