Most people don’t use many services where security is important. It’s not uncommon to have several hundred accounts with passwords, but I have maybe 10 that I really worry about being hacked/lost. For all the crap sites I can just use $singlepassword+$servicename as password. For the few sensitive ones I use strong passwords and 2FA. I do use a manager to keep those strong passwords - but even though I have it, I can’t be bothered to use stronb passwords for all those forums, web shops etc.

Is my solution secure? No. Using a bad password for hundreds of sites is definitely not secure - but the quality of a password only needs to be proportional to the sensitivity of what it protects.