Stress is a relative term. The stress an investment banker probably feels isn't the same stress as, say, a brain surgeon or a pro golfer or a hedge fund manager. There's urgency to the job, but it's more of a day-to-day urgency. You don't get to plan vacations far in advance, and you might get phone calls in the middle of the night if you cover foreign accounts managed by individuals who are, well, rude.
There's also the constant and ever-heavy weight of expectation following you around everywhere you go like a gloomy cloud. When you're dealing with peoples' fortunes, yeah, they tend to get pretty picky about how you do things. Frankly, we're not sure what could possibly be worth all the tireless labor and unending demands of perfection. Oh wait, that's right. It's called being a millionaire by the time you're forty.