... You've certainly given me food for thought. The way you've described it, one could argue that cryptocurrency lacks the fundamental trait that defines an asset. There's no tangible use or financial benefit to it, besides the abstract belief that its value will rise in the future.
Yet it still works, somehow. People still... put value into it.
What people do is put entries into the log. And they give things with value (assets) to others. That's how the scheme operates. Why people do that? It's like with every other pyramid scheme - they hope that new participants will give them more assets in the future. A we know why this collapses. Of course, bitcoin and shitcoins will not collapse as they are logs, and some copy of the log will always exists of someone's computer. The scheme where people give assets to others is what will collapse.