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 would like to add some more precious things as not just buying and holding Bitcoin for 10+ years rather switching it to the right cryptocurrency timely to get much higher returns on occupied assets in the real world. As for now, we are seeing many altcoins already jumped like a skyrocket boost. Investing in such valuable coins can also make anyone, not just a millionaire even a billionaire or trillionaire.
Still crypto is the initial phase, and since it comes to market, it has opened many new doors with new dimensions of business. Nowadays Defi, NFT, LP, Minting, Staking are on the fly. And in the coming future, there will be definitely a new era of the decentralized world that will explore new business models to the world.