I have been wondering what the annual rate of bitcoin loss would be assuming that bitcoin was the world's currency.
I'm guessing that the largest contributing factor to the number of coins lost each year will be the loss due to people dying and leaving them behind their computers never to be used again.
So I've internet searched and discovered that in the European Union the crude date rate is 10 per 1000 (ie: 1% of the population die each year), the USA is 8.2 per 1000 (0.82%), China is 7.1 per 1000 (0.71%), Japan is 9.0 per 1000 (0.90%), India is 8.2 per 1000 (0.82%) and Russia is 16 per 1000 (1.6%)- my calculations give about 8.4 per 1000 (0.84%) as the date rate of the combined population of the world's largest economies.
However, the problem is likely to be a factor bigger than losing 0.84% of all personal cash holdings each year, because the people who die are more likely to have larger cash balances then those who don't die. This is because those past middle-age have an ever increasing chance of dying while at the same time these people hold more cash than those younger. Older people hold more cash because to a mature person with other assets a $500 cash holding is a relatively smaller amount and also less useful to them then someone who is 18 years old on an apprentice wage or someone who is 28 years old with 2 kids and paying off a mortgage. i.e. young people don't hoard cash or hold large amounts of working cash as older people do.
Now you may say that people dying is not a problem, they just have to keep someone informed about where there coins are. However, I can't envision many people leaving instructions in a will or with a trusted person about their password and where they've stored their every-day-use bitcoins because the amount of cash involved is small compared to the total wealth of their assets and thus not worth mentioning. Not only that, leaving instructions has the extra hassle of keeping them up-to-date each time you change your password or move the coins to store them on some other device. (Similarly in the current state of affairs most people don't leave instructions in their wills about where they keep their physical wallets/purses). Where large stashes of cash are involved it is easily believed that the owner doesn't want anyone else to know since it reduces the risk of theft if no-one knows. Furthermore, for the case of extremely large stashes it is likely to be the result of illegal activity and they would be very reluctant to tell anyone (this scenario is even worse because people who engage in such activities -eg. drug trafficking- have an increased chance of dying).
Of course, in addition to all the coins lost each year due to people dying there will be a very small percentage lost due to negligence and mishap. eg. people forget passwords, accidentally delete wallet files, suffer hardware failures, etc. and not have a backup of the coins they have lost.
All up I would guess that at least a few percent (it would not surprise me much at if it was even as high as 5%) of the current year's coins will be lost each year.
I'm curious to know what members of this forum forecast the loss to be?
(PS: You could of course view this as a gift from the dying to the living-- the value of the coins that aren't lost should rise in value by at least this much).