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 think this is the same case with every investment where its price skyrocketed in the market 5-10 years ago.
I started investing in BTC back in 2017 where its price was relatively equal to roughly ~$4,000. Unfortunately, if I had just HODL my BTCs, I would have earned roughly around ~$40,000 in BTC which would have helped my family in relieving the expenses incurred.
Though this may be the case, this fully taught me on how to HODL my BTCs for long-term gains. Given the inflationary nature of BTC, its price would inevitably skyrocket the more it reaches to the points where every BTC would be mined out.