Not that similar. The reward-to-effort ratio for attacking LastPass is much better, you'll gain access to the passwords of so many users. With Dropbox, its less likely that you'll find something valuable and therefore less worthwhile to try. Most users would store their vacation photos, perhaps income tax info which might be useful but not as instantly exploitable as passwords.
Plus the password database is likely encrypted with a decently long master password and encrypted with AES (assuming this if the user has gone to the trouble of using a PW manager with Dropbox sync, hopefully with Dropbox 2FA also). That should be enough to keep out virtually all hackers, barring perhaps a nation state. For an extra level of security, you can (with KeePass at least) require a master password and key file (perhaps stored offline on a USB key), which will likely keep out virtually anyone.
