There's a tradeoff between security and convenience that has to be dealt with. You're not supposed to reuse passwords, but most sites/apps require a login. How do you memorize a couple hundred passwords? An offline vault is safer, but also a real hassle to keep synchronized between devices and locations.

I've settled on memorizing passwords for financial sites and emails and storing the rest in a password manager. All I can hope is that, should a breach happen and my passwords somehow get decrypted, I'll retain control over the most critical accounts.