It is, if they are encrypted. Without a password manager, I would inevitable have to reuse the same passwords over and over on my hundreds of different accounts. With a password manager, they are auto-generated random gibberish. And yes, even when using 2FA, you should have different passwords for all accounts.
Bitwarden, OnePassword, LastPass, Proton Pass etc. are password managers with dozens of millions of users that agree.
It's not, because the world we live in isn't binary. It's not true that "it's encrypted therefore nothing can go wrong". Putting your password manager online increases the risk of an accident.
And just because millions of people think this is a good idea, doesn't make it a good idea. Millions of people also reuse their passwords and that doesn't make it a good idea either.