there's a good expansion on this topic:
Monkeys on a Typewriter - Introduction to the Survivorship Bias
Rohit may wish to see:
about his "stock portfolios bleating in real-time with every loss"
Another of Taleb's pages discusses the "peso problem": strategies that offer
low volatility high returns, until one day when something unforeseen happens
("exogenous shock") and the position tanks. I am reminded of the world at the
beginning of the century: a globalized economy, assembly lines providing the
atoms, telegraphs providing the bits, and Taylor and Fayol providing the New
Paradigm. No doubt they could have done much for Progress, if it hadn't been
for that pesky Great War.