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.
Most of them was, because that's what an investment do multiply the capital. So, when an investor sees an opportunity he would in no doubt sell especially when Bitcoin was at a very early stage back in the days. Nobody would have thought that it could have a value as much as $60,000 in just 11 years.
However, there might be a few people who trusted Bitcoin and sold them in 2015 or 2016 when Btc reached a thousand bucks. Who would have thought It could be more than just a thousand bucks back on that days as well.