> To make money as a trader, assuming your motivation is to make a profit, you need to buy low and sell high. Not to pic a nit but most traders also sell short

> To make money as a trader, assuming your motivation is to make a profit, you need to buy low and sell high. Not to pic a nit but most traders also sell short, i.e. reverse the order to make money; (borrow stock) Sell High and Buy Low (return stock). The guy seems pretty smart so he probably left this out to keep his explanation simple. Side note; Short selling serves an important function in price formation and liquidity and is not the primary cause of a stock price to fall. In fact, for the short seller to make profits there must be an independent cause of the fall apart from the short seller's actions or they lose money.