As simple as it is to understand this trading strategy, some folks consistently do sell below entry price. Buying low and sell high can be effective in raising your profit to a new level but you have to be discipline to achieve profit with this strategy.
It is not so easy to buy on low and sell on high. If so then why thousands of investors lost their money. Everyone in this world works for making money and not for losing. When the price downs demand for crypto is increased and suddenly the price moves on, because price depends upon demand. It is very hard to find a chance of buying coins for low price and sell on high.