Crypto is mostly used by the young generation of the current world and it can be said that they are updated with the current world. They know the current world very much. Smart and easiest way to invest in crypto without going regulatory process which most of them want to ignore. This can be the best explanation for this statement so far.
In addition, young people are usually more open to new things. Of course, background also plays a role. If you grow up with certain technology, then you are more likely to have contact with newer things. I think that's why more young people are currently investing in crypto than in stocks.