You probably don't use a lot of different software like I do. For example my work computer is encrypted at boot in the BIOS and I need a password for that... There is no password manager available during BIOS boot up to fill in the password for me. Or I need to run a legacy application in a less popular browser or in the terminal/CLI where the password manager is not available and I don't want to open my vault and manually copy my plaintext password in front of my colleague who I'm currently screen-sharing with. I've had times when I was temporarily locked out of the password manager or I my laptop was wiped clean after a mandatory laptop swap/upgrade at my company (my work is confidential so there are a lot of security protocols I need to follow).

Once, I lost the master password of my password manager and the email to reset that master password was sent to my email inbox which required a password which was stored in my password manager which I was trying to regain access to... Catch 22... In the end, I got lucky that I didn't trust the entire security model and I had written down the password for my email on a sticky note on my desk!

The reason I lost the master password is because my company made me change the password every few months and didn't let me reuse old passwords and forced me to use a specific sequence of special characters. Eventually I couldn't remember which of the last 10 passwords I used was the latest one and which special characters were not allowed for which environment.