In the 10% range like the normal societal expectation (or requirement if you are religious and actually follow your religion but mine wasn't religious giving). Was higher when I made good money. Dragged down by a decade of not doing well.
My lifetime giving is more than I paid for my current house. The house in discussion for him is just one of how many that he owns? Or how many boats that count as 'second homes' under tax rules? Also consider he has paid for the entirely of this house, the average person giving 5-10% hasn't come close to paying for their house, so you need to go based off the 'already paid' amount. Also their home would be their largest asset, so going by that his largest asset for comparison would be his stock holdings, an order of magnitude larger than the cost of one of his homes.
Old boy is a billionaire, not a rando, and has proven he has zero shame. Despite starting their companies with techno-optimist claims, the robber barons had more shame/were more decent people/supported society more than the average tech billionaire.