I used to be on a biohacking/nootropics discord a decade ago. People were trying to treat their depression by ordering research chemicals from Russian labs or synthesizing them themselves. Huge difference between that and going to the GP and getting a Prozac prescription, with semi-regulated supplements being in the middle. That's analogous to ordering peptides from sketchy suppliers, getting a GLP-1 prescribed by a doctor, and getting a peptide facial from a medspa.
I would assume that an order of magnitude more people are getting prescription GLP-1s than are ordering other peptides from online suppliers and injecting them.