At high school you could have learned statistics and probability but never heard about the Arc Sinus law because it was discovered by the statistician Levy only lately (even on search engine you would barely find a link). This law is different from more famous Laws from the same Levy which concerns no-mean and no-variance family of laws. Some statisticians have given to the Arc Sinus Law the metaphorical name of "Fundamental Injustice Law of Nature" - but leave the consequences to the Philosophes . Why ? Because this law says for example that at a fair coin game between 2 players chance will have tendancy to ALWAYS favor CONSTANTLY the SAME PLAYER for a LONG TIME so that persistency of apparent trend of the fortune of this player is in fact totally due to chance since the two players here have no special advantage one above the other. Some gurus have profited from that to show that some people could win at casino and stock market with only money management without specific knowledge of market (which is in this is case a soft word for martingale and pyramiding scheme). Yes some people could win but it doesn't change the fact that if they continue the game LONG TIME ENOUGH the chance will finally revert. That's why if you only count on chance and you make gain especially huge gains thanks to pyramiding the best decision is to STOP once you reach the fortune. If you make gain and have real knowledge of market's action you have more chance to escape ... this chance's law. Some technical analysts even use this law to justify that trend exists in stock market whereas it cannot be used to justify the existence of trend from the statistical point of view and in a conference on Finance and Chaos Theory a Mathematician in the field has mocked precisely the abuse of that law to make a false justification by showing a chart from a technical analyst with a trendline and justifying - falsely - with arc sinus law. P.S.: why is it called arc sinus law because the sinus is in the expression of the law but it is not important for the subject discussed here.