I think a number of us just genuinely disagree with your general viewpoint that carbon bikes are commonly know to be weaker, don't last as long, the reasons why people buy them, etc. We own carbon bikes, and know a number of other people who also own carbon bikes, and haven't found any sort of big durability issues.

And there's no basis to say that "Carbon bike owners don't buy carbon bikes for the longevity of it. Owners of carbon want stiff performance for climbing and/or sprinting doubled with a smooth ride." I don't mean to attack you, but it would be difficult to not get irritated when you phrase your opinion like it's common knowledge - and you're wrong. Plenty of people buy carbon bikes assuming they will last 20 years or more (not the components which will wear out, but the frame itself). And I would say that the most common reason for someone to buy a full carbon bike do so for completely and totally non-racing reasons - they buy it because it's a smoother, nicer, and less fatiguing ride with skinny tires than an aluminum or steel frame would be. Even if you felt that this wasn't true (and I think it is true), that's the most common, or one of the most common, reasons that inspire people to spend the extra money.

You're certainly welcome to your opinion, but if you phrase your opinion as your opinion you'll generally get people who agree or disagree with you, but when you phrase your opinion as fact or common knowledge you're going to get a lot of flack if other people disagree with you.