I have never broken a carbon component. I have watched a rider come to grief when his carbon seatpost snapped when he was in front of me on a descent at over 30 mph. It was spectacularly horrible but, miraculously, he sustained only bruising and a broken thumb.
Oh, and I doubt if he weighed more than 150 lbs.
Stuff breaks. Titanium breaks, steel breaks, aluminium breaks. It makes sense to stay within the specified parameters for whatever one rides, but carbon is no more intrinscially liable to failure than any of the other materials.