The medical companies already sold the debt to debt servicing companies. It’s the debt collectors who are profiting, or (more likely) taking less of a loss on bad debt.
Also, they didn’t pay USD$15 million. They paid $150,000 to buy $15 million of debt at a penny on the dollar.
The organization that does this acknowledges that it’s a stopgap in the face of the human rights nightmare that is the USA’s healthcare system. It’s palliative care or harm reduction but not a long-term solution.