This subject came to my attention recently.
I started getting emails with the following text in them. I did some searching and it was very interesting what I found. We all know of hackers, but the scope and types of data being hacked means, well, anyone can have their passwords made publicly available by hackers. Some of my old passwords are now publicly available. (not important ones, and they are changed now) Using the same password for lots of accounts is extremely dangerous. More so if you also have these attached to the same email address. Using keyboard pattern passwords seems also to be risky. Simple words with a few numbers added are very common. The best way is using word phrases, like, MyFavdogisLAB. Adding a number or special charachter makes them pretty safe. Eg My2Favdog9isLAB or MyFav&dogisLAB (nothing I would use) Use some sort of password manager. I use Keypass. There are many more available. The little green book works well also.
Check this site to see if your email has ended up in a list: https://haveibeenpwned.com/
A reddit thread on the subject that is very active recently.
Some interesting reading: