I've been around a while, Ridden several bars to breaking. Bars break. Just a matter of time. High quality ones ridden not too hard and not crashed, sometimes a very long time. But crashes, strong riders ... can mean even the good ones have been stressed and doomed to a much shorter life.

The older the bar, the smaller the diameter and the thicker the wall thickness, the more likely that the failure when it happens will be "gentle". I had a late '60s GB bar (a lot of miles, how hard unknown) bend 30 degrees at the outer edge of the reinforcing sleeve when I dropped the front wheel into a winter pothole. It was 5 miles later when I looked down and noticed. Rode another 5 miles to my training partner's house, checked the train schedule, a mile to the station and another home. Recently I was riding to the local velodrome 2 miles from my house when I chased down a sound to a tiny crack in the same area on a modern, nice set of bars. Rode gingerly (uphill) to the track. Put in a word to the announcer to please ask if anyone was going home in my direction. No way was I going down that hill to the stop sign!