They Can Blackmail You
Scammers and hackers might use any information they find in your email account to blackmail you. They could do anything from making sensitive information public to using your email to send inappropriate emails to your coworkers or loved ones. They could use this leverage to try to blackmail you for money or worse.
There are many things you can (and should) do if you get hacked, but the first thing you should try to do is get control of your account ASAP. As soon as you know your email has been hacked, try to reset the password and make sure to close your account on every other device.
If you’re using the same email and password on other platforms and websites, you should also change them in case someone tries to log in.
You should also try to contact your loved ones or people you work with and tell them that you were hacked. Let them know that they may get emails from you asking for help or money, but that they should call you to confirm it’s actually you.
Another thing you should do is make your passwords stronger. It’s best to use different passwords for different platforms and try to enable two-factor authentication whenever you can. That won’t make your accounts completely unhackable, but it’ll be way harder to log in without your consent.