Selling your Crypto Currencies does not mean you are selling low all the time, most of the traders are selling anytime and any kind of market condition as long as it is profitable and they will earn a profit by doing it. Professional traders always find an opportunity whether the market is in a bullish state or in a bearish state and there is nothing wrong about it as long that the person knows what is he/she doing and knows the risks of this kind of industry.
Lots of people with weak hands sell as soon as the first sign of trouble appears. People who makes big money are the people who HODL through tough times.
But people who make even bigger money are people who do trading and take advantage of the market situations with due diligence. Hodling is a good way to earn a profit in the long run and I agree about it.
