Before using a password manager: I'm using short, memorable (often repeated) passwords that are rarely, if ever, changed.
After using a password manager: I'm using long (generally 64 characters), unique passwords, and if one is compromised, it's a 30s job to change it on all of my devices.
Convenience _enables_ security. I could probably roll my syncing solution, but I would _not_ be convinced it is secure (I don't have that level of expertise), and I would probably end up using a third party anyway (Dropbox/Digital Ocean). I'm not going to sync it manually to the 6 or so devices I regularly use, plus others I use less frequently (it may be more secure, but it's not practical). Because it's low friction, I end up using it more, so it's a _net_ gain in security, even if it isn't perfect.
