Resolves YES if a credible argument can be made using solid evidence. With a lot of wiggle room given to the YES side. That is to say, there does not need to be a study specifically targeted at adults aged 30-40. If it seems likely that a majority of adults possess crypto currency, this resolves YES. This market will only resolve NO if it is very clear that the number has never approached 50%.
This only counts if those people generally intend to benefit from possessing the coins, either from selling them or spending them. If there is a marketing stunt that involves giving a tiny amount of crypto to each American, or something similar, it doesn't count.
This question intentionally does not specify a specific crypto currency. It will count any currency based on the blockchain that fits the spirit of the term "crypto currency" as it is used today.
As I will be judging the question's criteria favoritably towards YES, I will not be allowed to buy YES. However, I will be allowed to buy NO stocks if I so choose. I will not be allowed to sell NO stocks, they will be locked in until resolution.