I know two early adopters cases (close friend and friend of that friend) where they cashed out way too early, at around ~$200. They both got back in later but at the higher price and interestingly they are not bothered much with the fact they could have been millionaires now, which is a healthy attitude ofc.
That's sort of the beauty of Bitcoin... Those who came in to get rich quick made a quick investment profit and bought dumb shit (remember Goat buying a Lamborghini after selling his 1000 BTC coin, where is he now?) while those who actually believed in Bitcoin and weren't in it for the money found themselves as integral parts of various organizations that kept BTC coming their way even as it appreciated far beyond anyone's expectations. This is a trend that always continues and the market is great at separating the two classes. Try and earn interest on your BTC, lost. Try and use leverage to trade, lost. Try and cashout to buy a dream home thinking you're a genius and the gains will always continue to pay a crazy mortgage, lost. Try to get involved with Bitcoin because you care about freedom and want to build new use cases, well... those folks are still here.