Doing it long-term way is the wisest thing to do.
You will cherish every moment of it once a person understands why he hodls and what will be by the end of such a journey.
Nobody knows or can know what would become of Bitcoin or his investment on the long-run, we're only optimistic that Bitcoin continues to perform well and appreciate in price and increase the value of our investment. Yes the person can continue to understand why he holds of which apart from securing his financial future, people might have other reasons for building up their Bitcoin portfolio and holding for long.
However, one can decide to take some portions of their profits only if they invested for very long like about 4-10 years, it would be very foolish for one to sell every Bitcoin in their wallet just because they've invested for a longer period they can choose to sell some portions and channel into other business areas and generate more income to keep adding Bitcoin to their portfolio but taking profits should strictly be when they've invested for a very longer period and not below the full circle.
Everybody is at liberty to do whatever they wish at the end of their holding period. For example: A person who invested into Bitcoin throughout his working years and held for 30 years is already a long-term holder and he can decide not to deal with the volatility of Bitcoin at his old age and sell of his investment to take care of his much older years.
Again people hold for various reasons, a person can be investing into Bitcoin for the purpose of starting a very profitable business venture at a much later time, and after like 10 - 20 years of investing and reaching his accumulation target, isn't it wise he achieved his dream? Perhaps he may wish to his sell off and achieve his dream and resume investing from the proceeds of his business.
Some other guy might wish to keep holding and only shave off profits in bits to take care of himself at the expiration of his holding period.
All these scenarios are valid, everyone is at liberty to do whatever they want with their Bitcoin at the end of their holding period, although I'm likely going to be the third guy, but It's entirely my decision.
It wouldn't be wise to sell of all yout bitcoin investment that you took a very long time to build and grow to your target. Selling all of it means that you don't value your bitcoin portfolio because you will sell and hold fiat that will continue to depreciates whereas, your bitcoin investment should be giving you more profits overtime if you continue hodli and shave off profits once in a while. This is because the value of bitcoin will still grow beyond your imagination.
Whatever investment that you sell all your bitcoin and put in will not give you the profits that you long-term investment bitcoin portfolio will give you in the long run, and your investment will be affected by inflation since it is a fiat business.
If you have reached your bitcoin target does not mean that it's selling time, rather you have just transit to your maintenance stage. You can only think of selling part of your bitcoin when you have accumulated more than enough Bitcoin.