Human subjects research, for one e.g. very often they involve clinical populations that are very hard to recruit. You can spend tens of thousands in advertising, and multiples more in labor, to get a hundred participants in, over the course of an entire year of effort, and that's not even counting the money spent on a clinician doing a diagnosis. And then, when you do, you may, say, pay $1000 for the MRI per subject, plus the $100 bucks you pay directly to the participant themselves.
Human subjects research, for one e.g. very often they involve clinical populations that are very hard to recruit. You can spend tens of thousands in advertising, and multiples more in labor, to get a hundred participants in, over the course of an entire year of effort, and that's not even counting the money spent on a clinician doing a diagnosis. And then, when you do, you may, say, pay $1000 for the MRI per subject, plus the $100 bucks you pay directly to the participant themselves.