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Yes, he knows it already, that is why he already have a 1 BTC but maybe he got bored lately and he also saw the headlines about those old and new altcoins who were pumping unexpectedly. That makes him more encouraged of trying them. I think investing in a tiny amount wouldn't hurt even when our altcoin investment fails. We still have more Bitcoins left and there is always a chance for us to recover what we lost in the past.
If we are sure that the coin that we hold won't recover anymore, then there is no point of holding it anymore. This is often the case that happens in the new coins or hype coins. For those who don't have a patient to HODL longer, Bitcoin will still be a bad choice for them because the real potential of BTC doesn't come out easily.
Lemme clarify something we don't always understand about altcoins; Altcoins are being created to distract you from focusing on bitcoin there were lots of altcoins created almost with same utilities and concepts but the difference there are just names and probably network configurations, at this point those projects that almost has same similarities between them are always competitive and most times they died unexpectedly after investors noticed the most useful project they dump one for another.
As an impatient holder or investor you might end up with one of them which may result in total dump on you. Must projects owners knows the facts and may not want to revealed their true intentions towards his or her project. Like you said, over hyped projects often always end up this way due to much attention gain would makes them dumped quickly after investors might have noticed some slack back and weak points or has came to realize the reality behind the project.
However, let us have this at the back of our mind that no investor planned to hold any hyped coin or shitcoin for longer all their intentions are being centered on profits aspect, so they invest for short period that is why as a crypto enthusiast the ability to outsmart others makes you a champion and a top leader.
Then as a human I would also want you to view another points from project owners, when they noticed their projects is gradually dropping and declining what they does is to come with another strategies either by paying some famous cryptocurrency influencers to come make some noise on their projects to enable them gain attention, those who never noticed the project would definitely come to invest and if they do those who invested then might be lucky to sell and make their profits then leaving empty tokens to newbie investors that is when you always hear their cry talking about their investment is gone.