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?
If you can manage to time your trades correctly then selling bitcoin for the short term is a great thing beacuse you can get out of bubbles and get in when nobody is talking about bitcoin, much like 2 years ago when bitcoin is floating around $200 constantly.
Bagholding for the long term does not always work. You may encounter for example personal expenses that will force you to sell your bitcoins anyways, or you may just not be patient enough to hold bitcoin for such a long time.
Short term selling is really not an opportunity loss if you are planning on entering the market again. When the price is sky high right now I would even argue that selling would be the smart thing to do - wait for the dip in price and buy in. Make sure that you have at least 20% in btc at all times though, because the prices are extremely unpredictable and it could just skyrocket overnight and you don't want to lose out on that.