Even the wealthy can't escape their craving for attention, and charity is their most "cost-effective" tool. After all, a donation leads to endless media exposure, and their public image skyrockets. On the other hand, it is precisely because of these celebrity stunts that the public’s focus is drawn to distant social issues.
Sometimes it is other times it is not.
The late great owner of the New York Yankees George Steinbrenner donated millions in medical gear to New York State Hospitals with out taking any credit for it at all.
A lot of rich people do this. So they are not looking to be known as donors.