They don’t store the password, they store the cyphertext where your single longer password is part of the key. If you wanted to do things that way yourself, my

They don’t store the password, they store the cyphertext where your single longer password is part of the key. If you wanted to do things that way yourself, my understanding is that you’d be just as secure if you stored the cypher text in a file on your computer. Also these companies provide nice integrations with web browsers and OSes which makes using complicated passwords easier. It’s true that a hacker with your master password would own the keys to your life, but that’s often true in general: despite repeated requests to not have a single password, most people have a one or just a few passwords they reuse everywhere. This is a better way because you can focus on remembering one big password, add 2FA, and have unique, complex passwords everywhere else.