Maybe Satoshi's storage media deteriorated beyond repair and he lost all his bitcoins. If he had them on a flash drive it might have broken, the silver surface on his cds/dvds might have peeled off, or the ink on his paper wallets might have faded away. We should back up our keys every year to be safe.
I doubt that, but it could be... The problem I have with moving your information from one storage media to another as the technology change, would
be the exposure to new security risks. I create all my paper wallets on computer equipment I destroyed. If I have to re-scan and re-print them... let's
say... when it fades, then I have to make sure I duplicate the same process offline or I will increase the risk of losing those coins. I reckon laminated
paper will not fade within 5 years... and if they do, you would pick it up early enough and replace it. I still have document without lamination from 9
years ago, and it hardly fades at all.