You're wrong, in Bitcoin investment, the big right thing to do is jumping in and buying regardless of the market sentiment as long as you've discretionary income present.
You don't just sell because your Bitcoin is profitable, else you can be going for short-term gains. You sell (if at all necessary) at the end of your long-term holding period in order to get the desired profits.
A big hit is accumulating a decent portfolio and holding for a long-term ( 4 -10 years or longer) so that you can have a chance to maximize your profits potential and not worry if the price goes low or high since by then the compounding interest on Bitcoin price appreciation would've acted on your holdings and possibly, you'll be very profitable depending on how long you were able to hold.
As an investment that has reached his accumulation stage with his long term of 2-3 cycles or more, it is adviceable not to sell all your coins but to take your profit and continue your journey or sell part of your capital and have some left which you can continue with because it will be wrong as an old investor to sell all your portfolio and start from the scratch that is from zero level investment that will not be good at all, except you are not interested in Bitcoin anymore.
The fact is that being a no coiner all of a sudden after so many years of accumulation doesn't sounds or look good in my own opinion because selling everything off to me feels like you are no longer interested in Bitcoin or making money through it, but if you are truly a big fan of Bitcoin selling everything off after the end of your accumulation and holding journey is not the right thing to do because you automatic becomes a no coiner, and starting afresh will be very discouraging for you to even consider it again because to accumulate a very huge stash of Bitcoin will actually not take a day or a very short period of time to achieve easily, so taking profit gradually is the best approach if you have gotten to such level of accumulation in the future.