Those are good thoughts about selling only when you must. Those that have plans in the longer run, there is a bigger plan if you are not going to sell now. Some have already sold even before crossing $100k mark and that's fine, it's their plan and goal that must have been hit.
But if they have no plans of accumulating again, they're missing the bigger part. IMHO, if something big has already been achieved on their lives with the help of Bitcoin, that's okay.
We only live once and we don't know if we will still be alive tomorrow and so, selling for those important matters and events of their lives, there should be no form of making them regretful.
Of course, we only live once, but we can still hope for a better tomorrow. Our job is simply to try and pray and hope - beyond that, we never know where the end point lies. Of course there is nothing wrong with selling when they need and want to sell it for various reasons - it is none of our business. As long as they sell it at a profit - then it is fine, but the biggest loss is when they rush to sell when the return is not worth it with the risk they took during the investment.
Taking profits when returns reach 3 to 4 times the investment budget is quite satisfactory. Few assets can deliver such high returns over a few years. So, once they've achieved that, selling isn't a problem.