Your provided link does not take me to any kind of survey results.

Regardless, I think it's safe to assume the Stellar Foundation polled their own users, and not a representative sample of the general population. "Cryptocurrency enthusiasts use cryptocurrency" is not exactly an interesting or surprising survey result.

The link includes an invitation to download the report leading to these survey results:

https://www.pymnts.com/wp-content/uploads/2021/09/PYMNTS-Cro...

The survey results I saw, the important citations I didn’t see is how they extrapolated the results to represent anything more than the responses of 2,079 people that are interested in surveys about cryptocurrency and cross-border transactions. Therein lies the rub.

So what does this have to do with 8 million people?

If the survey was of 2,079 people, then how does this extrapolate to 8 million? They say 23% of the respondents represent 8 million people, but that does not mean that 8 million people actually used crypto.