One reason that has not been given, but may be the actual reason why many people buy and hold Bitcoin is its use as a betting instrument. That is, you buy it paying X dollars today in the hope that you will get >X dollars when you sell it at some time in the future. Of course, if it has no other value than that of a betting instrument, then this is really a game of "holding the bag" with the last people out getting screwed.
That is dead wrong. I mean, it's correct for probably 80% of the people dealing with Bitcoin, unfortunately, but the point of buying Bitcoin should never be to get more shiat coins back. That is the mistake of high time preference people!
You are also assuming things on your own. See, many things end up getting value because more and more people end up agreeing with that idea. But that's what markets are made of.
I can give you an example that sometimes happens to me that makes me thinking just like that. Like "who decided that the word <spoon> represents an object that allows you to take objects into your mouth?? Why not <priche>, <glast> or anything else"?? Note: those sets of chars are only that. Sets of chars that I put together randomly! No idea if there are words like that!
So, when you say that something has value, maybe it gets real value if more people agree with that! Someone decided, and others agreed that <spoon> could be a set of chars to represent the object that allows you to carry objects into your mouth. I know that words has their own etymology, but I think you get the point.