Even just as a speculative bet that moves quicker than the stock market, it has value. Some people are seeing wealth they would never have had a chance at if they did it the traditional way of investing in stocks and bonds, and it's transforming their lives (and a bunch of other people, unfortunately, have lost money, sometimes a lot of money, on the other end as well).
I joined a video game startup that ultimately failed and probably lost out on at least $100k or more on money I could have made during that time at a larger corporation, especially since I didn't have a 401k then (I got paid, but a lot less than I would have elsewhere).
It was a speculative bet that I made and I failed. I don't really see how that's much different than someone making a poor bet on crypto (assuming they only spent what they could afford to lose, of course).