I had two clients from America I want offer graphics designing jobs for, I demanded my payment would be in Bitcoin
BTC or Ethereum. To my greatest dismay, they were dumfounded on what Bitcoin or Ethereum is. I am still suprised up to this very moment.

maybe he doesn't know the current technological developments or he may never use the internet so he lags behind the information that is trending in today's world
Or maybe he's too old to adopt changes in our modern technology and finds it very complex so he/she doesn't know how or don't want to use it. According to a report, the average age group of cryptocurrency investors is 37-44 but I've noticed that there is plenty on the younger generation too that are using cryptocurrency.
While in the other study, it shows that 18-34 years old use cryptocurrency.
Here's the study where I learned about the ages of the crypto investors;
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3501549##https://cryptobriefing.com/surging-interest-bitcoin-vs-gold/