I worked in other fields before IT. Sure IT is stressful. Every job is stressful, if you let it be. I'd much rather work in IT than work in a control tower at a big airport! I'm not sure why, Jack, you would think that younger people handle stress better than older people. I've seen exactly the opposite in my own experience. Maybe you saw some "old guy" melt down and that colored your perception?
As far as the other implied "old guys can't cut it in IT" conjecture, I've seen rookies come and go where I work, and they can't stick to a problem more than a half an hour (and that is being generous) before they give up and move on to something else. My theory is that they are products of the 15 seconds commercial/click a new link for a new subject/140 character text message generation. Completely pulled in so many directions that sheer concentration is impossible for them. Not their fault, but it's there.
Hey, I just realized that I'm a ageist too!