Investing is the intersection of economics and psychology. The analysis is actually the easy part. The economics, the valuation of the business isn't that hard. The psychology - how much do you buy, do you buy it at this price, do you wait for a lower price, what do you do when it looks like the world might end - those things are harder. Knowing whether you stand there, buy more, or whether something has legitimately gone wrong and you need to sell, those are harder things. That you learn with experience, by having the right psychological makeup.
Seth KlarmanDo not trust financial market risk models. Despite the predilection of some analysts to model the financial markets using sophisticated mathematics, the markets are governed by behavioral science, not physical science.
Seth KlarmanWhile knowing how to value businesses is essential for investment success, the first and perhaps most important step in the investment process is knowing where to look for opportunities
Seth Klarman