This is a good question but not an invalidation of the study. People underestimate the cost of doing large scale surveys, first year researchers become painfully aware of it. There are lots of research were you try to get a quantitative result cheap. But most costs a lot of money (the big studies are usually very well spent money imho)

Example: five years, 10000 participants, $170 million https://www.nih.gov/news-events/news-releases/nih-awards-170...