In August 2015, Turing Pharmaceuticals and its then-chief executive, Martin Shkreli, purchased a drug called Daraprim and immediately raised its price more than 5,000 percent. Within days, Turing contacted ... PSI, a charity that helps people meet the insurance copayments on costly drugs. Turing wanted PSI to create a fund for patients with toxoplasmosis, a parasitic infection that is most often treated with Daraprim. Having just made Daraprim much more costly, Turing was now offering to make it more affordable. But this is not a feel-good story. It's a story about why expensive drugs keep getting more expensive, and how U.S. taxpayers support a billion-dollar system in which charitable giving is, in effect, a very profitable form of investing for drug companies - one that may also be tax-deductible. PSI, which runs similar programs for more than 20 diseases, jumped at Turing's offer. PSI is a patient-assistance charitable organization, commonly known as a copay charity. It's one of seven large charities ... offering assistance to some of the 40 million Americans covered through the government-funded Medicare drug program. A million-dollar contribution from a pharmaceutical company to a copay charity can keep hundreds of patients from abandoning a newly pricey drug. Fueled almost entirely by drugmakers' contributions, the seven biggest copay charities, which cover scores of diseases, had combined contributions of $1.1 billion in 2014. For that $1 billion in aid, drug companies "get many billions back" from insurers.