I don't know, msybe because young people are more open to change and haven't had a set niche to get used to snd are usually more adaptive to new, exciting and innovative things in their lives. But then again, saying this across all young people wouldn't be true because again, some young people are hipsters and would want to be set in their ways.
Although I know a man of 63, who is trading actively, I suppose there are not so many people of this age do it. Young guys are eager to try everything new. They are surely opened to the cryptocurrencies and ready to trade.