Just having a reused password doesn't mean you can instantly hack it. If it's reasonably complex you're not going to brute force it.
The real danger comes from shit like this:
https://www.wired.com/2011/05/sony-online-entertainment-hack/https://www.wired.com/2015/08/happened-hackers-posted-stolen-ashley-madison-data/https://www.msn.com/en-gb/money/technology/ancestrycom-data-leak-rootsweb-server-accidentally-exposes-300000-email-addresses-and-passwordsIf you re-use the same password everywhere, and ONE of the companies you give your password to fucks up, it can get leaked out into the world. If your password at
Ancestry.com was the same as your password to e.g. your email, or your online banking account, you would be extremely fucked.
Everyone fucks up, even huge companies. If you give your bank password to Sony or Ancestry you are giving them the possibility to take you down with them when they fuck up.
And this is assuming everyone on the web is honest. What if some shady website site tries to get you to register just so you they can check to see if you re-used the same password/email combo elsewhere and hack all your accounts?
of course 80% chance you don't actually have a friend you're trying to convince and you just want 4chan to crack someone's password so you can stalk them
