Any bike, regardless of material, will last longer than most people want. Forgetting about C&V, who wants to be riding on a 20 year old frame with all the improvments since then? Sure, you might have a serious crash that causes damage. But for the most part (disregarding individual tales of my XXX frame material suvived when frame material YYY wouldn't), serious damage isn't dependent on material. Just buy a frame that fits you and you like.