Many posts discuss the possibility of exchange earnings with selling Bitcoin (and buy later). Other posts discuss the Bitcoin exchange rate, it seems that many agree there is a strong upward tendency and the volatility is hard to predict. It seems dat selling Bitcoin results in a serious probability of an opportunity loss. Selling Bitcoin can only be motivated by an (partial) exit. Do you agree?
Selling bitcoin during the growing trend is a huge opportunity loss. However, there's more than one right thing so it would be wrong to say for certain.
It depends on the situation. If you are going to hold bitcoin even when it has reached your target but since greed has overpowered your senses, you are going to lose in this case because it takes a second to enter dip for virtual coins.
Similarly selling off when the market or bitcoin is facing harsh dump is the worst thing that you could veer do to yourself and your money. Panic selling is the biggest mistake with bitcoin.