I have trouble believing 9% of the US population owns crypto.
Thats 30 million people. Coinbase has 11 million active users including a large proportion of foreign users. So maybe 9 million US users which is 2.7% of the population and instinctively feels more realistic.
This might be your culprit:
internet-connected respondents
A lot of rural and older people don't really use the internet. Same with children, and I doubt the indigent are responding to surveys like these. How they define "internet-connected respondents" must inflate the numbers; it sounds like a more tech-savvy crowd than average. I saw a recent survey that said 5% of the U.S. population owns some cryptocurrency. Even that sounds like too much.