[camel_Snake]

AFIAK FDA doesn't regulate what you, yourself, are legally allowed to consume but rather what companies are allowed to market as drugs and legally distribute as such.

For example you can bring your own non-FDA approved drugs with you to the US for personal consumption. I found the following document, section 9-2 covers this topic: https://www.fda.gov/media/71776/download?attachment

[freedomben]

That's a fair point, although the FDA (IIUC) has power to say whether some drug must be gated behind a prescription or can be over the counter. For over-the-counter stuff I think you have a good point, but for prescription drugs (which I'm sure is all or nearly all of the interesting drugs) they are gatekeepers.