How Retail Investors loose money?

The reason is simple - a retail investor is driven by greed or fear. Never logic.
Retail investors are always the last to enter a bull run
"Smart money" enters markets long time back when markets are at its bottoms, there is frustration all around and no one wants to discuss markets
When markets start booming and indices make new peaks, the retail investor "wakes" up. At this stage, he is still not sure and is a fence sitter. Lastly, there is optimism all around. Every one is bullish and talking markets. Stocks which were never traded in a year, suddenly start moving and start reaching "new highs".At this time, the retail investor starts buying as he does not want to miss out the "action"
The retail investor will display a marked preference for "low priced" stocks because these are "cheap". He will stay clear of index stocks as these are "expensive".This is also the time when "smart money" starts moving out
When a correction happens, it is usually quite severe-The retail investor does one of two things. He either decides to wait (the optimism is still there) or he starts "averaging" his costs. Averaging is nothing but trying to "catch a falling knife"
At some time or the other, panic sets in. The retail investor will then sell off all holdings as a distress sale.
Sometimes the retail investor will do nothing but wait for the markets to rise. When the markets do rise, he will sell off all his holdings at the first available opportunity and thus miss out on the new bull run.
In a bull run, the retail investor is usually the first to sell off his holding. This investor seldom waits for the bull run to continue.
Those who have never participated when the rally started will invariably jump in towards the end of the bull runRetail investors rarely follow stoplosses. Circumstances eventually force them to take a bigger lossLastly, retail investors spend an insignificant amount of time researching an investment as compared to buying a mobile or fridge.