It's not like we know what the future might hold plus, at that time people are still uncertain and the Internet was still rife with scams so the people don't trust new things from the Internet immediately plus the FUDs were really strong back then, bitcoin being used for scams, black market, and drug trafficking, any sane person will doubt it's credibility when something like this happens.
I know it may not be as profitable to hold it now as it was back in the day, but can you really doubt bitcoins rise? I have seen many people who doubt it, but I have made a lot of money over their doubts. Bitcoin is something that will go up, it could have downs here and there time to time but we all know it will be a lot more than what it is right now.
People who trust this and invest accordingly made enough money to be happy about it, and there are people who didn't make any money at all from this because they were doubting bitcoins capability of going up. I believe in the long run bitcoin will always go up, even if there are 50% drops like we had recently from 60k to 30k, eventually it will always go up, the new ATH at around 64k will be broken, the price will be higher than that, I just do not know when but I know it will happen. This is why I keep buying bitcoin as much as I can with the money I have, in order to keep investing into it, I do not know when I will be capable of selling it, I could now and still profit, but I just believe it will go up so I do not sell.