I wonder how many of those who invested early on actually managed to hold long enough. I joined only around 2015, and even I remember a time when $600 per BTC felt like such a great price. Apart from selling, it was easy to lose coins due to scams, locking yourself out of your wallet, or accidentally making transfer mistakes.
But no matter when someone invested, surely it was hard not to sell at some point. In the grand scheme of things, I agree it's not too late to invest, but people should do what feels right to them.