Those giant university endowments are partially used to allow those who couldn't afford it but otherwise have shown they have what the university is looking for in students to attend for significantly/entirely reduced costs. Meanwhile, the most visible billionaires are using their money to try to buy elections so they can dismantle the government for personal gain while oftentimes employing people with such low wages that they depend on the government to be able to afford such luxuries as eating three meals a day. It's pretty easy to see why the large parts of the public find one acceptable and the other less acceptable.