One dose is one thing -- but there are other risks that can lead to complication or death here if taken improperly for a long period of time. Musculoskeletal issues, cardiac issues, thyroid issues, etc.

Additionally, getting the correct dose is not straightforward for a layperson as it is for other OTC drugs with standard doses.

There are similar risks, and probably more likely, to all sorts of consumables that aren't regulated at all. It is reasonable to ask whether the prescription regime for GLP-1s makes sense. It isn't the only substance posing that conundrum! Ondansetron is OTC in a lot of countries, but not in the US, Canada, or UK. But ondansetron is arguably less dangerous and more helpful than pseudoephedrine.