[martamoreno2]

If you are using a weak password, that's always a problem...

But a masterpassword for offline storage is a completely different story, because even if the world knew your masterpassword, they still couldn't do anything with it, because they need to get to your dropbox file first.

If you use similar passwords everywhere, any site can read your password and use it to login somewhere else... You are supposed to use long random passwords for websites because you have to assume that every single password gets compromised and the website you are on tries to hack all other accounts.