The patents covering Dataprim expired decades ago. The only leverage he had with the existing drug was that there was no other licensed producer of it that was an appoved manufacturer with an FDA license for the manufacture of the drug as a generic.
This was bound to be resolved, as once the cost to set up production and obtain an FDA license for it made it feasible for other manufacturers (like all kinds of generic makers here and in India) to produce and market Dataprim as an FDA-licensed generic.
He just realized that in the interim period, there would be zero competition and he could charge whatever he wanted.
There are a LOT of generic drugs that are simply uneconomical to manufacture at the prices paid - you may recall there are and have been a number of shortages of old, generic cancer drugs recently. That is because the cost of manufacture (principally the costs of FDA licensure for process (and facilities) and maintaining licensure) and the huge growth in product liability lawsuits (notice all the lawfirm ads on TV trolling for any user who thinks they can tie their medical problem to every drug and medical device under the sun) make it an uneconomical business for many generic drugs. The price caps for Part D Medicare and Medicare/Medicaid users contributes to the problem, since there is no incentive to create or expand aproduction capacity for a drug that is nott going to make munny, net of all-in production/distribution costs and product liability lawsuits.
So the 'authorities' have created a niche for guys like Marty to buy the entire current production capacity of a drug which has no good substitutes and then milk it until one or more other generic manufacturers decides to make an investment in licensure and production capacity because the price has gone up and it now makes sense to try and make it profitably.
