The reality is that they would not have been able to hold for so long even if they bought 10 years ago. Very few have the patience to wait till 100x or more. Most of the investors will be sold at the idea of 2x or 3x itself. Some of the people that were able to hold for so long were those who had invested and then completely forgot about it. There is one more category of people who had complete trust on BTC and thus they stick with it for years.
I could not agree with you more, it's in the nature of the people to sell it if they manage to make their profits to as much as 3x. And really, there's only few who manage to hold their investments for 10years and that falls on the category of people who make many investments other than cryptocurrency. Also, bitcoin isn't that quite famous and trustworthy 10 years ago than it what it is now. The idea of holding bitcoin for a few years was I think only began on 2016 up until now and only sell the profits.