如果那兩百人的地理位置隨機分布，結果就是偶然的。
可假如那兩百個贏家都來自同一個地方、師從同一個老師、用同一種方法拋硬幣，那結果就有其必然性。
--- 巴菲特
Mark Spitznagel 、做空次貸那些人的方法從性質上說都類似，他們能賺大錢的結果就是必然的。
絕大多數人即使被告知了那種方法也在實際操作中做不長久，這就是為什麽股市裏絕大多數人賠錢了事，隻有極少數人賺了大錢，還有少數的賠賺不多、打了醬油而已。
THE SUPERINVESTORS OF
GRAHAM-AND-DODDSVILLE
by Warren E. Buffett
https://www.tilsonfunds.com/superinvestors.html
Before we begin this examination, I would like you to imagine a national coin-flipping contest. Let's assume we get 225 million Americans up tomorrow morning and we ask them all to wager a dollar. They go out in the morning at sunrise, and they all call the flip of a coin. If they call correctly, they win a dollar from those who called wrong. Each day the losers drop out, and on the subsequent day the stakes build as all previous winnings are put on the line. After ten flips on ten mornings, there will be approximately 220,000 people in the United States who have correctly called ten flips in a row. They each will have won a little over $1,000.
Now this group will probably start getting a little puffed up about this, human nature being what it is. They may try to be modest, but at cocktail parties they will occasionally admit to attractive members of the opposite sex what their technique is, and what marvelous insights they bring to the field of flipping.
Assuming that the winners are getting the appropriate rewards from the losers, in another ten days we will have 215 people who have successfully called their coin flips 20 times in a row and who, by this exercise, each have turned one dollar into a little over $1 million. $225 million would have been lost, $225 million would have been won.
By then, this group will really lose their heads. They will probably write books on "How I turned a Dollar into a Million in Twenty Days Working Thirty Seconds a Morning." Worse yet, they'll probably start jetting around the country attending seminars on efficient coin-flipping and tackling skeptical professors with, " If it can't be done, why are there 215 of us?"
By then some business school professor will probably be rude enough to bring up the fact that if 225 million orangutans had engaged in a similar exercise, the results would be much the same - 215 egotistical orangutans with 20 straight winning flips.
I would argue, however, that there are some important differences in the examples I am going to present. For one thing, if (a) you had taken 225 million orangutans distributed roughly as the U.S. population is; if (b) 215 winners were left after 20 days; and if (c) you found that 40 came from a particular zoo in Omaha, you would be pretty sure you were on to something. So you would probably go out and ask the zookeeper about what he's feeding them, whether they had special exercises, what books they read, and who knows what else. That is, if you found any really extraordinary concentrations of success, you might want to see if you could identify concentrations of unusual characteristics that might be causal factors.
