Market cap is equally irrelevant. $10B is ~8% of his net worth. His biggest gain in net worth was 2017-2018 where it grew ~$80B, which would make $10B = 12.5% o

Market cap is equally irrelevant. $10B is ~8% of his net worth. His biggest gain in net worth was 2017-2018 where it grew ~$80B, which would make $10B = 12.5% of his 'pre-tax income'. Donating 1/8th of your pre-tax income to charity would typically qualify as reasonably generous, no?