1) Because ROI on that investment is still positive, even if it used to be “free”.
2) Endowments aren’t the only way to fund research, and not all research is equally valuable. Some is probably negative value, given the replication crisis.
3) Investment income from the endowment is taxed at a maximum of 8%. If that’s enough to break the US university research machine, I’m not sure it was ever working in the first place.
The ROI is not positive because there is no guarantee basic science will lead to any money-making outcome. That's not how basic science works and it is never how it worked, but basic science is absolutely crucial for advancing tech. If you can convince shareholders that it is e.g. worth investigating unusual crystal structures with no intended product in mind then people will gladly share some grants with you to edit so you can work some of that magic. It's just not feasible, no company would pay for that, but sometimes it leads to important discoveries that change the game.
And I only mentioned endowments because the parent of my comment did, but again, the important point is that endowments are not intended to entirely fund the research machine, and never will.
On the frontiers of knowledge, people furthest out know what problems need to be worked on and what research needs to be done. You don’t need the government blindly throwing darts at the wall hoping that one of them hits a bullseye and calling it “basic science”.
I’m open to the idea that government can play a role here, but only in a very small way. The government is spending hundreds of billions of dollars on research. They are such a huge consumer of talent and resources that they are crowding out private initiative. This ain’t Bell Labs of the 1950’s. And if you asked those researchers what they think of today’s system, I’m sure they’d be appalled.
Look, I'm going to be honest -- your comment here tells me you have very little knowledge of how scientific funding, or even the scientific process in general, actually works. Would you like information on what is actually going on? I'd be happy to explain it.
I love it when people use the phrase, “I’m going to be honest,” because it implies that previously you were lying but are now choosing not to. But given that you haven’t explained anything as you happily promised, I’m going to assume you’re not just a liar but also ignorant of how scientific funding, or the scientific method in general, actually works.
The cumulative ROI for basic research is positive, but I don't think that is true for many individual research efforts, which is what a company is more likely to support. An individual company seems much less likely to benefit enough from an aggregate pool of research that they will actually contribute. Look at the state of open source software with respect to company investment in maintainers.
2) Endowments aren’t the only way to fund research, and not all research is equally valuable. Some is probably negative value, given the replication crisis.
3) Investment income from the endowment is taxed at a maximum of 8%. If that’s enough to break the US university research machine, I’m not sure it was ever working in the first place.