The survey is a paid online survey. The people that participate are not representative of the "American population". People doing online surveys are much more likely to own cryptocurrencies than the average American.
It is very important to keep this in mind when explaining the context of the results. Furthermore, by taking a look at the actual website, finder.com, it seems as if it has a big emphasis on money and finance, given how the default page itself is tabbed under "money" and includes items such as "credit cards, loans, mortgages, money transfers, banking and investments, etc." Cryptocurrency itself is a section of the page, which would mean that there is a very big bias in the result, as people who browse sites such as this one tend to already be familiar with money and crypto concepts, which would make them even more likely to be owners of such. From what I can tell, there were no other sources, as the graphs are also from that source, so there doesn't seem to be anything to reconcile this.