There are two related questions that bother me.
First, how much funding is enough for fundamental research? What criterion should be used to decide how much money is the right amount to spend on fundamental research?
Second, the human race spent a lot lot more on fundamental research in the second half of the twentieth century than it did in the first. It’s hard to get a good handle on exactly how much, in part because it depends on what you mean by fundamental research. At a guess, I’d say at least 1000 times as much was spent in the second half of the twentieth century. Did we learn 1000 times as much? In fact, did we learn as much, even without a multiplier?