In addition it’s also great for asset protection. For example if he gave a personal guarantee on some of the Twitter debt, then moving money into the foundation (as long as his Twitter stint was not fraud) will remove that out of his name and make it untouchable to the banks.
He can now use those funds to support trips to Mars and other projects. For those projects the charity might pay his expenses - for example a flight to attend a meeting in Hawaii. He can even use the money to hire his kids. The kids would have a much lower (w2) tax rate so effectively he reduced tax but kept the money in the family.
Another thing people are missing is that it's not an income tax dodge, but rather an estate tax dodge. The money will remain in control of his heirs, assuring they'll never go hungry or want for a place in the world.
It also creates more opportunities to play with asset valuations to evade taxes (eg separate the financial and voting interest of some stock in a closely held company, then claim the financial interest is worth very little without the control interest). But it's impossible to know if this is actually being done without seeing tax filings, including his (eventual) estate tax filing.
To run the numbers on the 37%:
Charity: 5.7B deduction * 0.37 rate = 2.109B value of the tax deduction
Selling: 5.7B deduction * (1-0.37) = 3.5B value of the stock sale
In addition, the shares were at an inflated value - if he dumps 5.7B onto the market, it's going to drop the value of the remaining 100B of shares. Whereas by donating to the charity, you get the 5.7B deduction, and the fund you donated to does not even have to sell the stock. Even if the stock drops shortly after, such as in this case, he still gets to keep the large deduction. See https://dlj.law.duke.edu/article/insider-giving-avci-vol71-i..., illegal but unenforced.
Also, he can use the charity money anyway to pay for various things he feels like spending money on - other billionaires have used personal charities to settle lawsuits, employ their children / cousins, invest in businesses of friends, etc.
That $5.7B is still effectively his, untaxed.
A distressingly large slice of eligible voters don't even understand how marginal tax rates work. Which is, like, the absolute minimum to have any clue whatsoever how US income taxes are applied, what tax bills will actually do if they become law, and so on. I'd be surprised if understanding of how deductions work is any more widespread.
[EDIT] Not a great source, but it's in-line with the results I've seen from better ones in the past:
https://today.yougov.com/topics/politics/articles-reports/20...
Roughly half don't understand how marginal tax rates work.
Can't find data on how many US adults understand how deductions work, but I doubt it's better.
Almost certainly much much lower seeing as how a ton of people here don't understand how deductions work.