It’s a shame people’s username are most often longer and much more harder to guess than their actual passwords. More time is spent thinking of a unique username than password because most are already taken in sites with a huge userbase.
You should never use the same password for all your accounts and should always use a completely different password for your email, a password you use nowhere else. Recently a lot of screenshots of vandalism using singles.org email / facebook accounts have popped up.
Once a hacker gets into your email they can get all the other passwords you might use for different accounts. People don’t think hackers would go out of their way to hurt them personally but it’s usually the case that they get their hands on a database and just go through the list without personally knowing anyone, looking for financial data or just being trolls.
Many sites are hacked by script kiddies with no programming skills who lurk for exploits which they can copy and paste and use their favorite apps to try to brute force the passwords which are encrypted.