Because the government stills needs some money to do certain important things, and Buffett is ready to pay more taxes to help fund that, and says that other bil

Because the government stills needs some money to do certain important things, and Buffett is ready to pay more taxes to help fund that, and says that other billionaires and multi-millionaires should too. But I'm sure he never said he would give away his whole net worth for that. The government and the gates foundation do different things, and there can be a need for both.