Yahoo hack is a reminder that nothing is safe
The real lesson of the Yahoo hack, in which 500 million user account details were stolen in 2014, is this: any account details you enter into an online storage system will probably get hacked at some point. It might just be your email and (encrypted) password, or it might - as with Yahoo - be more details such as name, address, phone number, birthday and even answers to security questions you use to verify who you are.