Some investors got to bitcoin early, yet did not recognize what they had, so they end up selling way too much too soon, so instead of continuing to buy bitcoin and making sure that they are continuing to build their wealth, they see 2x, 5x, 10x or even higher levels of profits in dollars, so then they end up selling way too much too soon, and based on their own income, they are not able to accumulate nearly as many bitcoin as they previously had with anywhere close to the same amount that they had invested earlier.. .so yeah, maybe they will come around to buying bitcoin again, but it can become psychologically difficult to switch from an accumulator to a trader and then to get back into accumulating, becuase there may welll be a realization that BTC buys may well end up being made for way higher prices than the earlier sales.. so that causes psychological difficulties.
Actually you can't blame those early Bitcoin investors who sold their Bitcoin way too early because just like some people are gambling on altcoins now that was basically how the early investors where doing same with Bitcoin because it was just a coin that was new into the market so no one would have given their 100% trust as at then and it's almost impossible to trust any system that just got introduced and has not gotten much attention and recognition by a large number of people so that was what happened among those early Bitcoin investors but now that they have seen the growth of Bitcoin I believe they won't find it difficult to buy at a high price now when they try to consider the price they bought it years back so the most important thing is having the finance to start now because with the height we all are anticipating the price of Bitcoin to reach, it's still at an affordable price now and buying Bitcoin doesn't mean we should go an all in or buy 1 BTC at a go, they can basically start accumulating now and hodl a reasonable amount that will boost their portfolio in time coming. I understand the psychological difficulties you are talking about but they don't need to continue dwelling in the past as Bitcoin has even proven to be more trustworthy now than when it was earlier invented. So the only thing now is to accept the mistakes of the past and move on to start making accumulations.
I doubt that I am blaming early bitcoiners for selling, since we can make investment choices and even selling choices, and then we have to live with the consequences of our actions, and surely some folks learn from their experiences better than others. And, whether someone considers it to be a mistake to sell too much too soon, and yeah the way I am describing it is as a mistake because a lot of people do not realize that they are selling too much too soon until later, and sometimes they make the same mistake over and over and over. Other folks learn techniques in which they might still be able to sell, but not to sell too much and not to sell too soon.
There are also folks who spent 1- 2 cycles mostly accumulating BTC before selling any... so yeah, some folks recognize the value of what they have earlier than others.
And, yeah, knowledge about bitcoin has changed over the years, but people are still making the same and similar mistakes including NOT recognizing the value of bitcoin, which seems to be part of the explanation why we have so many no coiners and low coiners. It could well be that somewhere close to 99% of there world's population is comprised of low coiner and no coiners, and no one is going to buy bitcoin for them, they have to figure it out for themselves and take action...otherwise they will remain low coiners or no coiners.
I believe we who are now the current set of investors are at a better advantage than earlier investors and we can actually learn from the mistakes they've made and ensure that we don't repeat those mistakes.
I doubt that we can avoid mistakes. We have to do the best we can with the information that we have, and sometimes we are going to make mistakes because we might not sufficiently figure out how to tailor our approach to our own circumstances, and so we likely will have to tweak our approach from time to time, since our information might change and also our circumstances might change and we have to make choices about how to balance out our approach to attempt to best account for those changes in information and/or circumstances.