At te very least with a good chunk of it. Again diversification is good.
This is the crux of the issue. If you have $100 million and you can't think of a single worthwhile use for any of it besides making more money, that's either a literally unbelievable lack of imagination, or incredibly cruel. It is so, so easy to do a huge amount of good with that much money. It's not easy to figure out how to do the most amount of good possible, that's probably an unsolvable problem, but it's not necessary.
I understand that investing in the stock market is supporting the economy and increasing liquidity and potentially helping a company and that's all good, but it is laughably easy to think of something better, if you don't need to worry about a financial return.
After all, you wouldn't want me telling you how to spend your money.
Something of it smacks of hypocrisy. I think you should be guilted into donating 5% of your wealth by that reasoning. Yeah you don't have 100M, but just like them a 5% donation won't materially affect your quality of life. How do you feel about that? Do you still feel it's anti social behavior not to do that?
Because I call hypocrisy otherwise.
If you have $100 million dollars, and you're investing in the stock market purely because that's the way to get the highest financial return, that is not rational, unless money is literally the only thing you care about. Presumably there's something else you care about, like the environment, or some political movement, or eradicating malaria, in which case investing all of your money in making more money is not the best choice. You probably still want to invest some of it, to maintain your lifestyle and maintain enough cash to use for the stuff you really care about.