Dropbox doesn't make you "constantly" update your password. Six months ago, they had a security breach, and required all users to update their password.
https://krebsonsecurity.com/2012/07/dropbox-password-breach-...
https://krebsonsecurity.com/2012/07/dropbox-password-breach-...
I'd delete my comment now, if I were still able to.
Personally, I don't think I've been back to the Dropbox website since I reset my password!
My reply was merely a "mea culpa", and the note about removing the previous comment was more about removing inaccurate information than about saving face.