The contents of this article notwithstanding, I'm not sure I feel comfortable with that kind of broad generalization. I'm sure there are a number of reasons why individuals would chose to serve in such roles, and like any large organization or industry, I'm sure there are people who fall within a wide spectrum of ethics or morality. I wouldn't necessarily think there are any more psychopaths in the military than there are in Silicon Valley.
As a counter point, albeit one steeped in personal anecdote, one of my best friends whom I've known since childhood, served a number of years in an elite military unit, and continues to do so in a slightly less elite Air National Guard unit, and he's probably the most honest, charitable, and fiercely loyal person I've had the privilege of knowing.