selling bitcoin at $108k in other to buy back cheap when it dip depends on how long you have hold unto your bitcoin investment if you have hold your bitcoin investment from 4 years and above and you sell in other to buy back it's good less take for example now, less say you bought bitcoin around 2015 when bitcoin was between $150k and $500k if am not mistaken and you sell when bitcoin was $108k it is good investment.
As long as you didn’t sell at loss, then it’s a good investment, when you invest in bitcoin, even if you don’t make so much profits then it’s fine, what am always after is that we shouldn’t sell at loss. Mostly people that do make huge profits from bitcoin investment are people holding for long term, people holding for short period of time do make just little amount of money, that’s why when we are planning to invest in bitcoin for maximum profit, then our target should be for long term.
Your post looks like you are encouraging trading, you should understand or know that investing for short term is same thing as trading and anything trading, the return or profit is not guarantee that is to say that one may not even be in profit in that short term so it is better one stay off from investing for short term ( trading) because they will definitely panic or sell at loss and instead of all this unnecessary pressure and selling in loss why not just invest and hold for a long period of time which is best and preferable way to go about Bitcoin investment.