Real professionals are ofc selling when the price is high and buying when the price is low but to know when which level of investment is necessary is complicated in the best of times and the blockchain/crypto-currency market is still way too volatile and "new" to get through by using basic stock market knowledge. Problem is ofc, every action by every single investor influences everyone else - it's a bit like a soft version of the prisoner's dilemma: If no one sells, it is good for you to also not sell, but if a lot of people sell, you want to be one of those....so you need to trust either 1) "the market" ...hard...or 2) the long-term-correction-tendency. To be fair, a good investment won't be underrated for long but trusting the market in general - especially on the short term - is....brave.
All people are doing the same. It is the rule of supply and demand. People buy for low price and sell for higher price. Cryptocurrency business is not easy. You may lose your money due to fall in the price but you can make a huge amount due to rise in the price.This is the right way of doing business in crypto world. Patience is also mandatory in crypto business.