It could be to some people who are good at da trading stocks. I personally pick my horses carefully and hold long term.

However, I did sell and reinvest during some Bitcoin spikes (for example, I sold when it was nearly at 3000 before it lost value last month). In some cases it is a lot of speculation and more luck than skill, however, sometimes the signs are pretty clear and you definitely should take profits. I never sell my whole position, but a part of it, e.g.: 50% and rebuy more coins if I turn a profit. The more secure I feel about my judgement the larger the position amount I sell.