If Martin Shkreli, the young hedge fund manager-turned-pharmaceutical executive who made news last month by jacking up the price of a life-saving medication by 5,000 percent, was surprised by the scorn his decision provoked, it was because his behavior was rather common.

Our brains are wired to believe that good things are more likely to happen than bad. It can make us underestimate our risks.

A group of researchers now claim to have conducted the first comprehensive study proving that wellness programs can produce a financial return on investment for employers.