Well cryptos is still an obscure technology only used by 500K-2M users around the world.  If you look at something like social media, the oldest person on Facebook is supposedly a 103 year old great grandmother.  I have happen to met several retired pensioners with tablets / computers, smartphones and facebook and yes some were older than 80.

Plus it's a fact that old people like their spend their money on the lottery, so it's probably a good thing they don't know yet about crypto currencies or the grand children's graduation present will probably be squandered on $hitcoins.