I suspect that there are a lot more coins lost forever than we might even imagine. Only I knew two guys (personally) who had more than 30k btcs combined, all lost. First one had hdd failure but as bitcoins didn't have any value worth mentioning back in the (very!) early days, he didn't bother with data recovery and simply threw away the disk. Other one died unfortunately, and later I've heard from his family that his PC has been wiped out, reinstalled, and given to someone as a gift.