I do agree that a lot of people tend to do something like this, but that doesn't change the fact that we are going to end up seeing people fail at it as well. Like sell your btc for fiat/stable and then the price goes up, so you fail to get better amount, that has to be the most important part.
In a bull run that lasts for some months, more than one year, holding is key to get best profit. What you described is a most common mistake do touch during a long bull market. Want to maximize profit but we all can not predict the market well and accurately so we usually sell high with hope that market will correct down, then buy higher. We will still get profit by doing this but we will lose our bitcoins with it.
I believe that the best thing to do would be just holding. This is why people hold, there is no reason why we believe that we can't make any money, we can definitely make some money, we just need to make sure that we know what we are doing, and usually that's the hardest part. I believe that readjusting to the market price is hard, and while we hold, that is a lot better and we just keep on making a lot of return by simply holding.
Holding is best in a bull run. By holding, we also have a best preventive layer to avoid touching Margin, Leverages and Futures that bring bigger risk than trading with Spot. As said above, trading with Spot in a bull market is already bad enough for us to lose our bitcoin. With Margin, Leverages and Futures, it will be only worse and worse.