Selling your bitcoin too early isn't a good way to preserve the compounding value of your bitcoin portfolio even though you have reached your bitcoin target.
Investors are not expected to sell that early, except when after they buy in the dip, the market quickly rise and they were able to marginalize a reasonable amount as profit over thier short time investment, then they can sell to reinvest and continue to hold, but in most cases, i do see investors as long time holders as you have said, because they are willing to have thier asset preserved over time without losing out, and they make more profits as the market rises and they can comfortably sell at bullrun when it is pumping fast.
You contradict your points here and you are obviously proclaiming that invstors who bought the dip can start gambling with bitcoin in the pattern of selling and reinvesting. Of course I can never agree with that strategy. Investors should be very intentional about their accumulating bitcoin and not engage in trading activities like selling to reinvest because it creates a shift in the mindset of an investor to start thinking he can have an accuracy of timing the market and buying back cheaper.
What if after selling to reinvest and bitcoin price never comes down for him to buy back cheaper? the investor finally buys back and ends up with fewer coins because he has chosen to be trading bitcoin at a time he should be investing into it. Additionally, as the prices begins to go up and never come down, the investor turned trader may keep waiting for the price to come down and maybe never buy back if the price keeps going up and this might stagnant his accumulation journey and at worse case scenario might even weaken his motivation and he ends up jeopardizing his accumulation journey