Warren is full of contradictions for anyone who has been following him for a while. He will go down in history as one of the greatest investors ever, however admits to missing a great many opportunities and being clueless about technology. It annoys me slightly when he says people should not diversify if they know of a great company, because while it holds a grain of truth even the best companies can have moments of shock that can cripple them and it would ruin the small scale investor. Even Berkshire Hathaway is just a conglomerate of many dozens of private companies and share holding in publicly listed companies - itself the greatest example of diversification you could see in business.