Diversification

While we're on the topic of Buffett, I remember reading somewhere that he opined that diversification is for people who aren't smart enough to know what to invest in.

Count me in that aforementioned group.

So I would agree with him, but put it a slightly different way:

The less confident you are in your investment ideas, the more you should diversify. The more confident you are, the more chips you should put on the table behind that idea.