From the linked article:
Mr Shkreli said the price rise was to extract money from insurance companies to fund research for better drugs.
Can you imagine any other industry trying to do this? Like if you asked why a pair of headphones was so expensive and the salesperson told you it was so they could fund research for even better headphones in the future. Why would I want to pay for research for a product that's not the one I'm purchasing?
It's standard practice that the cost for research is factored into the cost of the finished product, not the inferior current product. And research is financed by investors who bear the risk if the research is unsuccessful or reap the reward if it is successful.
He says anybody in the US without insurance who needs the drug can get the drug for free.
This is how they get away with it - by hiding behind insurance companies. Instead of the cost falling on the person who takes the expensive drug, it's spread out among their entire insurance pool. So we're all paying for it whether we realize it or not. This is why 20 cents on every dollar goes to health care in the US.