Warren Buffett: Know-nothing investing

“And there’s nothing wrong with the know-nothing investor practicing it. It’s exactly what they should practice. It’s exactly what a good professional investor should not practice. There’s no contradiction in that. A know-nothing investor will get decent results as long as they know they’re a know-nothing investor, diversify as to time they purchase their equities, and as to the equities they purchase. That’s crazy for somebody that really knows what they’re doing. And you will find opportunities that, if you put 20 percent of your net worth in it, you’ll have wasted the opportunity of a lifetime, in terms of not really loading up. And we’ve had the chance to do that, way, way in our past, when we were working with small sums of money. We’ll never get a chance to do that working with the kinds of money that Berkshire does. We try to load up on things. And there will be markets when we get a chance to from time to time, but very seldom do we get to buy as much of any good idea as we would like to.”
—Warren Buffett.