In my previous company we hired a startup that did security training, that recommanded everyone use a password manager. And one of their test was that they sent a fake phishing email to people (randomized over a couple of months so not everyone would get it the same day).

I don't remember the exact number but something like 30% of people who didn't use a password manager got caught. Basically no-one using a manager was.

Granted there might be some selection bias (people who had managers were probably already slightly more security conscious), but people were feeling slightly embarrassed to have been caught and it worked great to have everyone do the switch. And everyone remembered after that that if it doesn't autofill, something's amiss.