It's a hard question to answer. Under normal conditions, supposing the bike was engineered and built properly, it shouldn't have a lifetime. That said, I remember reading a story about a prototype carbon frame that a major manufacturer was testing. It was super stiff, super responsive, but one day while the tester was sitting on the top tube at a light, it cracked in half. They didn't account for that force in the carbon layup.
Crashing is a different story. That would require more of a case by case analysis. I've been told the Felt TK1 sprint was designed with a different layup than the endurance so that it could survive multiple crashes. In general, though, I would say carbon fiber is more resilient than most people think. The issue really becomes a mental one. Without testing the frame each time, how are you really sure your equipment is fine? Doubting equipment can destroy your performance.
The first time I went up to Forest City, I had my bike with carbon handlebars. Going fast through those steep turns feeling the G forces, I was really starting to wonder if maybe I had knocked those bars around too many times, and I found myself letting off the gas just a little.