If there's a scrape in the outer clear layer that compromises the carbon underneath, or there's a small void in the carbon epoxy matrix, or the things are old with a lot of miles in them, they can snap. Even riding with a loose headset could potentially cause trouble.

Or yeah, you could drive into your carport with the bike on the roof and go for a ride the next day thinking 'She'll be right'.

Settle down gentlemen