It is well known that people are bad at taking drugs that work for them. This is particularly well studied when it comes to heart medication, the kind where you take it regularly or you die, and yet adherence is often around 50%.

From a quick search, Jarrah et al. (2023) "Medication Adherence and Its Influencing Factors among Patients with Heart Failure: A Cross Sectional Study" [0] discusses some of the relevant details.

[0] https://pmc.ncbi.nlm.nih.gov/articles/PMC10224223/

I know a couple who self identify as foodies and they started taking it for weight loss. They now complain that date night is no fun because they don't enjoy the food. They have not yet dropped the meds but I can see it happening soon.

They are very expensive

Cost.