I think better strategy would be Buy the DIP, sell at local high, open short, HODL and sell at local low. Rinse and repeat. Indefinitely. Yes, it is easier said than done. But for me, it is easier after around 6 months of watch, learn, and execute.
This is completely an off topic and meanwhile this thread is not talking about selling which sounds more of trading and gambling, but accumulating Bitcoin and hodl for a long period of time for like 5-10 years and the best way you can do this is to set aside an amount of income after setting aside your reserve fund or an emergency fund then use to amount to buy Bitcoin by using the DCA strategy which will help you to buy at regular interval either weekly or monthly.
The extension shouldn't be limited within 10 years but also as a lifetime process, not just accumulating for 10 years only. The process is for us to look in a long run, DCAing, sticking to our investment plans also not over engaging the process but developing a system that makes you consistent in your accumulation phase. If we treat it this way, we won't get tired but keep investing in our digital gold.
You can't keep investing all your life without having a time frame to take something out of the system. The time frame of 10 years he gave is enough to see some level of maturity and certain profit in your investment. Just imagine building a project without having a time frame of completion of that particular project so that you can embark on another one. After the 10 years the investor might consider removing some of his profit from his investment and from there he can set up another time frame and keep on his investment. The 10 years time frame doesn't mean that after 10 years he will stop investing no, what it simply means is that after the 10 years has expired he will harvest his profits and set up another objective of another 10 years or as he/she deem necessary. As humans as long as we are alive, we will keep on investing.