I'm not sure the argument that Ti lasts longer is really valid anymore.

I have 2 carbon mountain bikes that I've put thousands of miles on. Both are about 7 years old at this point. Early carbon as a bit fragile, but newer carbon seems pretty damned solid.

Even if you do break them, they are repairable. My wife broke the frame on her bike not long ago and she wound up getting it repaired. It was surprisingly affordable and the fix is likely stronger than the original.