Mar 26, 2021
Suppose that Distribution 1 represents nuclear plants. It has low variance, so all the plants are pretty similar. Plant A is slightly older and less fancy than Plant B, but it still works about the same.
Now we move to Distribution 2. It has high variance. Plant B is the best nuclear plant in the world. It uses revolutionary new technology to squeeze extra power out of each gram of uranium, its staff are carefully-trained experts, and it's won Power Plant Magazine's Reactor Of The Year award five times in a row.
Plant A suffers a meltdown after two days, killing everybody.
If you live in a region with lots of nuclear plants, you'd prefer they be on the first distribution, the low-variance one. Having some great nuclear plants is nice, but having any terrible ones means catastrophe. Much better for all nuclear plants to be mediocre.