> I think that if we legalize dangerous addictive drugs then we might as well legalize all medications/drugs by which point the medical establishment loses a big chunk of the income that it gets from being a monopoly supplier.

Do you seriously think this is why medication is regulated?

In most developed countries prescribing and dispensing are separated (doctor/pharmacy) in part to prevent this. Japan is a notable exception and guess what: more drugs are prescribed per capita there than the rest of the OECD.