How would that happen with 2FA set up? Even if they have your master password, how do they copy your Authenticator code or YubiKey or whatever else you might use?
I see people struggle with offline password managers to the point where they never use them or they get burned once because they're somewhere without access to their database and they stop using them. LastPass alleviates all of that. People make the same claims about TouchID (it's not secure, look at these theoretical bypasses, etc) but the fact is (which I thought I pointed out earlier) that convenient security is better than no security and no security is what you're going to get.
You think the government can't download things from your Dropbox and you think they can't decrypt your database? We know better now. The fear of "what if the government does" is completely gone. Even if they can't get to your password, they'll just go straight to Google or worst case scenario, straight to AT&T. The difference between encrypting like SpiderOak vs uploading an encrypted file like DropBox is that DropBox can hand over your password database to anyone they want to give it to. SpiderOak can't. You don't need to try to hide the fact that you have a password database, no one can tell in the first place. Security through obscurity isn't no security, it's just poor security and poor security is better than nothing (and far better when combined with good security).
You're using a password manager to keep your accounts safe from petty criminals and identity thieves, not from APTs or shady governments. And if you're using DropBox, the government probably already has it. I guess you'd have to ask Condoleezza Rice about that.
Use whatever you want, everyone has different needs and opinions. But I will continue recommending LastPass (and at the very least, strongly recommending against whatever + DropBox). Like I said, it's no less secure than whatever + DropBox. But it's a heck of a lot more convenient.