You are absolutely right, some people don't know that's why they are selling their Bitcoin hoping for it to dip for them to buy again not knowing that it is possible for Bitcoin to skyrocket or pump from this point and then dip maybe the previous point it pump from or it may not even dip to that point. Even if someone invested in Bitcoin some months ago before Bitcoin take this uptrend one shouldn't sell all his or her coin perhaps they should just sell some and still leave some and later continue there accumulation and holding so that it won't be like they are starting afresh because starting afresh is always hard and it requires a lot of determination and of course consistency to grow back again.
An investor who started his investment few months ago has nothing to do with selling part or all of his bitcoin, unless the person is just chasing after the few bucks and that's not encouraging at all for someone who has the mindset of long term hold, or call himself an investor. Even if the person starts his accumulation journey again at some point as you are saying, the person will still sell off, if there is also a future little gains, outside of his maturity date. If it happens that few months or one year later and there is another upward trends, the person will also sell and that's not how investor should behave. An investor who started his investment journey few months ago, has no business with selling not even one Satoshi of his bitcoin that has been accumulated. The focus should only be buying and should not be tempted with any little profits seen so far. People who thinks like that, or behaves that way are purely traders and they shouldn't confuse themselves as investors and people should not also refer to them as investors. And I don't think it's a good advice to give to someone in a thread like this, so that we don't confuse newbies who might be vulnerable to such an unhealthy advice.
Why will a new investor sell part of what he just accumulated, it means that he started his bitcoin journey as a trader and not an investor that he is claiming to be. Such person must be distracted from only buying and building his bitcoin portfolio which was his main purpose. A gambler must act like a trader because they are not ready to sacrifice their money into bitcoin for long and hodli but feel that they can outsmart the market but it will turn out to be that the market will outsmart them and take the little bitcoin they have being accumulating.
Bitcoin is not a get rich quick scheme but you are only investing in it to give you hope in the future. So why will you mess up with your future hope by not taking the right step on building your bitcoin portfolio through regular DCA every week for 4-10 years and above. If you're in your accumulation phase, you shouldn't sell a dime of your bitcoin, because everything starts one day, and before you know it, you will start selling from time to time making all your effort worthless. Look at MicroStrategy with all the bitcoin he has acquired, he still bought 21,550 bitcoin today to make his total bitcoin holdings to 423, 650. This should motivate you not to sell but follow MicroStrategy foot step, because Amazon shareholders has been motivated by Michael Saylor wisdom. Investing in bitcoin and hodli for long is wisdom and many people will remain poor because of lack of wise.