Martin Shkreli was trying to explain himself, so he turned to YouTube.

In the conference room at Turing Pharmaceuticals, the company he heads, his fingers flew across a laptop keyboard, and up popped a YouTube video on a large wall screen. It was a heartfelt appeal from three young brothers in North Dakota who suffer from a degenerative and often fatal brain condition. “Only 300 people in the country have this disease,” Mr. Shkreli said.

Why show the video? “I invented a new drug,” to treat the disease, he said, shrugging nonchalantly. “But it’s hard to sell a drug for 300 people, to go through the process. You have to charge a lot per person to make it a viable product.”

His point was that new drugs — especially for rare conditions — don’t come cheap and someone has to pay for them. This is more truism than earth-shattering revelation. But Mr. Shkreli has become a public villain for twisting that notion to apply to a decades-old drug that Turing merely acquired. By raising the price of that drug overnight to $750 a pill from $13.50, Mr. Shkreli became a caricature of pharmaceutical industry greed.

A former hedge fund manager, Mr. Shkreli drew the wrath of consumers, became a talking point in the presidential campaign, and spurred federal and state inquiries as well as a dialogue about how and whether to control rising drug prices. As proof of Mr. Shkreli’s toxicity, Bernie Sanders rejected his $2,700 campaign donation, turning it over to a health clinic instead. And in a sharp slap, just Tuesday, Express Scripts, the largest pharmacy benefit manager, endorsed the use of a compounded alternative to Daraprim, the $750 pill. That treatment will sell for about $1 a pill.