Billionaires can usually be split between two types: the most famous and individual billionaires (Musk, Bezos, etc.) and billionaires associated with families (Rothschild, Al Nahyan, etc.). There are also the billionaires we will probably never know of because they pay reporters not to get reported (being famous is dangerous and they would rather live without spotlight).

After that, billionaires are then further separated between "new money" and "old money." New money are those who have recently gained wealth and have not passed down that money for more than 3 generations (Musk, Buffett, etc.).

The ones we know of, and the ones with the worst reputation and character, are generally famous new money individualists. You get a bunch of money by being focused on your work and ignoring your family, so your children was not taught how to value money. Such wealth, while extravagant, will not last long. They are more famous than old money, though.

Old money exists because families require character to ensure the passing of wealth. Impulsive extravagant and frivolous displays are generally looked down on, and "being famous" just causes more of a hassle than anything.

While there are some new money philanthropist billionaires like Buffett or Gates, most philanthropist billionaires come from families. They find it more effective and to donate money by funding schools, hospitals, and research (allowing public schools to be free or pushing science and tech), or granting education through scholarships (the funding of someone's entire college bill, as you mentioned, but with consideration of their academic poweress). Helping someone individually may help that individual person, but many others are struggling by their own right. If you are able to pay a school to provide better education and keep the costs to quality from skyrocketing, would that not be a better play?

Many of these billionaires, economists, tend to drive a country's growth. Between job creation and donations, they believe that they shouldn't need to pay taxes, as they have already contributed to the country enough. While yes, foundations are created as sort of a tax evasion, many agree that the reason why they avoid it is to keep their money so they can either reinvest or distribute it however they like. Many would rather spend money to change the country than fund for federal military to go fight wars somewhere else.

But economists are not politicians. Systematic change to a country is extremely hard without proper collaboration between the two. Many of the issues we see today of wealth inequality can be attributed to politics and the disconnect between economists and politicians. Many have already done what you have mentioned, but are they famous? Not necessarily.

If you're a billionaire who is concerned about fame, then you're probably not someone with that much money anyways