That was basically the case for the drug that made Martin Shkreli famous.

(the drug was long out of patent, his company bought the FDA approved production line and such)

This is an interesting postulation and one I can support in theory.

My reaction though is tempered in the same way when I hear a US Federal Government person (ex: Secretary of Health) claim that a system of "Patient Empowerment and Patient Choice" is an ideal situation. I disagree. Looking at Health Statistics Reality (cough) a large portion of the US Population has made categorically bad decisions. Obesity. Heart Disease by way of contributing factors.

I get the rationale behind empowerment and allowing patients to find the "best" care around, but trusting Average Health Consumer to make Medical choices when they can't even get Dietary choices right is problematic.

If someone makes a drug and proves it safe, someone else could piggyback on that and say they're making the drug the same way, thus it's safe.