To be fair, I don't think anyone who has that much money will ever consider donating to NASA instead of going to space themselves. With that age and money, even the most humble and kind of people would much rather fulfil their selfish desires while giving their money to their own agencies. Blue Origin was founded back in 2000, it makes much more sense for him to invest in that himself.
On a completely different note, these simple space trips have pushed all big countries into a space race. There was no way they would work together anyway. So if they can consider finally investing in space technology by competing with each other, it's probably a winning scenario.
This is not my opinion on Bezos, of course. There were much better ways to spend the same amount of money by sending real astronauts and conducting research. No one needs nor deserves that much money.