Warren Buffett and Charlie Munger on Diversification

I have always tried to hold fast to this important fact. It has been with me a cardinal doctrine that I can manage my own capital better than any other person, much better than any board of directors. The diversification is for people who don't know what they are doing. Look at how all the great fortunes were built. He's like, listen, if you can invest in three great businesses in your lifetime, you'll become very rich.