From Charlie Munger at the Daily Journal Annual Meeting 2019:
Now ... we’ve done better than average. And why? And the answer is pretty simple. We tried to do less. We never had the illusion we could just hire a bunch of bright young people and they would know more than anybody about canned soup and aerospace and so on and so on. We never had that dream. We never thought we could get really useful information on all subjects. We always realised if we worked very hard we can find a few things where we were right. And that a few things were enough.