What works for Buffet just might not work for mere mortals. In fact, the data says it only works for 1 person, W. Buffet. Otherwise, there would be many people equally as rich from stocks. Besides which, he doesn't walk his talk. Berkshire Hathaway is all over the map, shorting the dollar, trading interest rates, buying a Chinese oil company, everything but hi-tech.
Each to his own, but I can't count the times that diversification has saved my derriere. I can count the times that lack of diversification was a disaster (1). I can't count the number of times that lack of diversification has been a disaster for other people.
The last case I saw was some poor guy that bought 470,000 dollars worth of a biotech before an FDA NDA panel decision. The ceo lied about the results and the panel voted 13-2 to deny. Stock was halted, gigantic gap down. Broker sold him out for a 100% loss. He was, it turned out, on margin and had all his funds committed to that one trade, no way to meet a margin call. Very foolish move and I wonder where he got the 470K in the first place. Didn't seem too bright, I suspect that it was an inheritance or something.
Market Data 
Markets 
AI
