[Bolding mine]I disagree that they aren't an investment. I would agree they aren't a smart investment - a 401k or a Mutual Fund is a smart investment, based on history, but crypto is still an investment - many people made a ton of money off of them. In the same way (& I know I'm repeating myself here) Beanie Babies were an investment at one time. Or baseball cards, or vintage comic books, or... I dunno, gold even.
My disagreement is simply that "speculative instrument"s can certainly be investments. Bad ones, or random ones, but sometimes good ones, too. None of these things have intrinsic value. Collectibles of any sort only go up in value as more people wish to acquire them. Or lose value as people cease to want to buy them. But they are still investments, in that the people buying them hope to make money later by selling them.