The people who make the "they're just doing it for tax deductions" argument give me the feeling that they don't understand what a tax deduction is. All it mean

The people who make the "they're just doing it for tax deductions" argument give me the feeling that they don't understand what a tax deduction is. All it means is that his taxable income will be whatever his income is minus that $10B. He's not getting a net benefit from doing this. To make the math easier, consider someone making $100k and paying a 30% tax rate. If they donate $10k to charity, rather than pay 30k in taxes, they're paying 27k in taxes. They saved 3k in taxes, but they still donated $10k, so they're out 7k. If his entire objective was to pay less in taxes, stashing it in the Cayman Islands would make way more sense than donating it.