Bitcoiners have less to fear from boating accidents, and more to fear from getting hacked. It is scary that your Microsoft Windows® machine is just one careless e-mail attachment click away from scrambling all of your data, and sending all of your money to heinous criminals who know how to make money disappear. Dont you wish that you had bought a hardware wallet? Such grief!
Microsoft Windows machine can be perfectly safe. Let's say it's dedicated to run your full node and nothing else.
What hackers can do in such situation?
What e-mail attachments, when you don't have an e-mail client on that machine?
You never launch a browser on that machine. Not once. So no phishing links.
Full node is the only thing that's running, and nothing else. And not as Administrator, of course.
No, the real problem is keeping your stash in one place, no backup copies (out of pure lazyness). Until one day BAM you lost it.