They can make the product they want. They can package it how they want. They can sell it for any price they want. You can buy it or not. It's the market at work. Competitors should come in and lower the price over time. Government should get out of the way, and Mylan should have told Congress, "No thank you, we'll not appear."
Sixty percent is a large space in pre-tax profit margin to be a "misspeak". The list product of a price simply needs to have the tax rates as well as production costs deducted from it to learn the current profit rate. Mylan would stand to lose a lot by telling Congress about the high markup of Epi Pens.
Yes, the CEO intentionally mislead Congress and the public simply to gain a bigger profit. This is one of the reasons that business people continue to get richer. They sacrifice the needs of their customers in order to fill their own pockets. The CEO will stop at nothing to make more money.
If the makers of prescription drugs don't profit from the drugs, there won't be any incentive for them to invent new medicines. They have to make a profit otherwise they will have no motivation to wake up in the morning and develop new drugs. They are not misleading Congress because they have been up front about their business model.