For noobs, HODLing is a term used for "holding" your assets (here: Bitcoins) for a very long time. But, isn't it true that those who bought it at $500 once should have sold it at $20k peak, and if not, why didn't they sell at $15k? BTC didn't crash all at once and they had the opportunity to sell and wait for another opportunity. A $15k per BTC against a $500 BTC - means a 30x return itself. And BTC crashed to $3k, if not $3k, then these hodlers would have bought back at $6k which is even less than half of $15k as they would also have added a lot more liquidity to the markets with too much money on the table. Isn't it true that too long a hodl can stop you from taking great opportunities while sitting dumb and waiting for a specific target?
That's true that you can miss opportunities if you keep holding, but when you say they could've sold at $20k or $15k the problem is that how do they know that's the top and it won't get another push to $50k, and when is exactly the right time to sell? you never know when to stop holding and it's the right time to cash out, for example for someone that bought Bitcoin at 100$ and sold it at $2k he still got 20x of his initial investment but he lost the chance to sell at $15k-$20k.
I'd say most people that don't trade regularly have problem to find the best price to sell and maybe they have a bad experience selling too soon and missing out on most of the profit they could have, because of that they prefer to hold whatever they bought for long-term till it has a significant pump to like 100x or something and then they can sell so that they don't feel that much regret, but I believe even though that strategy could work sometime you have to keep in mind when you don't sell something that already did like 10x and decide not to sell and wait more, it can as easily goes down to like 5x and you still have the more or less the same amount of regret that you didn't sell earlier, so in my opinion it's mostly based on luck more than anything else and that will be the deciding factor whether you made the right decision to sell/hold at that time or not.