Password managers are the definition of "putting all your eggs in one basket". You need to compromise 1 (ONE) password to get access to EVERYTHING. They are a lot more convenient, but barely more secure than a plaintext notepad file. And some people actually storing bank accounts and credit cards info there. This is insane to me.
It is exponentially easier to practice good security hygiene for exactly one password than it is for the 200 or so passwords/sensitive numbers I keep track of in my password manager. Maybe you are extremely disciplined and can remember 200 unique passwords/passphrases each with 100+ bits of entropy and are (effectively) mutually independent, but alas I cannot, and neither can the billions of people who use the same 8 character password for every account. The best I can do is remember 1 high-entropy password that I change regularly, and have the password manager keep track of 200 other highly-entropic unique passwords.
My point is that having a single point of failure maybe theoretically isn't as good as having a bunch of passwords, but in practice nobody has the discipline to actually maintain good security hygiene, and thus it is practically more secure to use a password manager than it is to have a bunch of different passwords that are either the same or closely related.
