I don't really have any problems with what you are saying, yet I still would like to quibble with the idea that after 8 years investing into bitcoin (presumptively accumulating bitcoin) the person would feel some needs to "take profits," since that just seems like a trading term, but yeah, sure, after 8 years investing into bitcoin, there might be some abilities to transition into maintenance or even liquidation.. but there likely would not be any need to rush such process to transition, and surely we are presuming that a person investing into bitcoin for two cycles might have had reached his accumulation goals, which may or may not be the case in terms of realities and potential needs to reassess where he is at and if he might feel that he can transition out of BTC accumulation and into some other variation that might be deemed as maintenance. He may well have to continue to assess his 9 factors in order to figure out whether he actually has gotten into some other stage of his bitcoin investment journey, and I still am bothered by calling whatever he does as "taking profits" since bitcoin is the most pristine of investments, but there still can be some reasons to balance and rebalance, especially after guys have reached certain levels of BTC accumulation.
I think this is where we are before shifting from the point. There is no perfect time to take profits from your Bitcoin investment I think it's a personal decision but an investor holding for 8 years can take his investment as long the purpose is to do something useful with the process. What I have kept in mind is that there are people who invest to maximize profits while some invest to maximize the volume of Bitcoin they have. People who maximize profits when they reach a target are more propelled to sell than investors who want to see their Bitcoin holdings grow more and more.
The safer way is that if an investor has less Bitcoin in his portfolio, he/she should probably hold. Selling quickly should be the last thing that cross his mind, while an investor who owns more Bitcoin at least more than 1 BTC, he can choose to sell little based on the situation or the reason for taking profits. However, it all falls down to your investment goals as the genuine reason for taking profit.