Which goes to show that Bitcoin needs to be taken very seriously. "Be your own bank" is tough. If you're not organized, not backing up your stuff, not taking such things seriously, Bitcoin's going to bite you in ways you never expect. It's going to mess with your head and even drive you insane. Same goes for any of us. Remember to always safely keep backups of your paper wallets and seeds, and make sure you clearly remember your passphrases and PINs. Periodically check to verify that you actually have access to your coins, this will refresh your neurons. Keep your keys away from online devices. Never take your PC/mobile to the repair shop when you have crypto in it (which you shouldn't have in there anyway).

After so many years of being buried under so much organic garbage, the chances of him finding the HDD and being able to extract the data are very slim. Still, an HDD is supposed to be a sealed container, although I believe there's usually a "breather" hole somewhere on the case, don't know what it's for, maybe to equalize pressure. If that's the case, and garbage juices and moisture got in though that, it's pretty much gone I guess...

$250 million is a lot of money though, and can get things moving. If he manages to find the HDD, he should pledge to give a very generous percentage of that to anyone who can extract the wallet.

Good luck to him, he's going to need it, especially if he's unsuccessful.