The size of the sample compared to the size of the population doesn’t really matter. What matters is how representative the sample is.
If they got a truly random sample (they didn’t), then 1000 is plenty.
Realistically, it’s probably 1000 Millennial and Gen Z Credit Karma users (already a niche group) who bothered to open an email and take a survey, which is not a realistic representation.
The size of the sample compared to the size of the population doesn’t really matter. What matters is how representative the sample is.
If they got a truly random sample (they didn’t), then 1000 is plenty.
Realistically, it’s probably 1000 Millennial and Gen Z Credit Karma users (already a niche group) who bothered to open an email and take a survey, which is not a realistic representation.