The pen & paper is not secure you might put it in your wallet and get it stolen, or a thief can visit your house, people from your close surrounding can read it while you're busy or sleeping. It's not a 50/50 it's just an unsecured way to store your password unless maybe you invent your own secret code to write it then put your paper in a good physical vault than it strongly screwed on ground/walls.... Of course you have to make sure to return the paper into the vault immediately after you used the password in case someone enters the room (you know smartphones have good cameras nowadays and the sheet of paper doesn't magically hides the passwords when the timeout is reached).
And then when you need to access your password from outside your house you realize you're screwed... and you blame yourself every x months when you have to renew your passwords and write them down again...
Use a good offline password manager... many passwords managers offers handy functionalities to store your encrypted password in the cloud (meaning on someone else computer), this is convenient, but it is the worst idea ever... unless you generate long random passwords and rotate them often and put them on your own private cloud... but still... forget about this option... just don't put your passwords in the cloud at all !
Also always prefer passphrases to passwords for your super important things you absolutely need to remember even if your computer/storage and post-its on your screen should ever burn. Complex passwords are just hard to remember, replacing O by 0, E by 3, i by 1, etc... don't make them more secure a meaningless phrase (which only has a meaning for you I mean), is much easier to remember and usually naturally meet the complexity criteria so you don't have any specific efforts on that side.
