People doing that is not really for long term since if they aim to hodl they would never think about selling their bitcoin when they see a pump and think about buying again when the price dump. The person who doing that are traders and I guess there's really a high risk for them to lose their money if they repeatedly doing this schemes. And won't recommend this to newbies especially if they don't know what to do next and much really better to anyone if they just hold their bitcoin and aim for long term since this will give them more decent result, also for that they would not get affected on any FOMO circulating around.
Does taking profit after holding for long in other to buy back when the price dips a great idea? Yes, it is. But right now, it is not advisable since bitcoin has the potential to go higher than this of which it is speculated that we are entering fully into the bull run. Imagine making a sell order at 64k, selling 20% of your BTC accumulation, and then you sit and wait for either 32k or below that. Only God knows how long it will take for Bitcoin to dip to that price.
I would always say that if you are selling let it be that you are selling for a good reason. People are out there selling at various prices this week because the price is rising significantly so they think that it is the right moment for them to sell off their investment and that someday the price will drop soon to buy more. It's just like dropping down from a vehicle and expect to run ahead of the vehicle for a cheaper cost. Let there be a reason for selling and make sure you have accumulated enough that if you sell some percentage, you know you still a lot in your bag.
The random selling of bitcoin for the sole of buying back when the price dips has left so many persons behind.
It is extremely difficult to time this market, the price fluctuations and uncertain movement would be a hindrance if someone tries to sell off to buy the dip. Just hodl and accumulate more now is the only solution to success, unless your target from the beginning was to invest and sell off when the time is right to pay for tuition fees or start good business. At least the target was to reduce financial burden, stress and enhance your life.