The scary thing is that citizens don't know how many plots these privacy invasions have stopped and therefore can't have an informed opinion on the matter and can't decide to fight back against these invasions of privacy. I'm sure plenty of plots have been stopped but would they still have been stopped without this information?
The scary thing is that it's possible. Personally I don't care of what they collect because I don't fear the present government. However I fear that any big entities can do the same or that any malicious group could infiltrate the government to get access to these data (or collect more).
The fact that we consider our online privacy as granted is the scary part.
There is a fundamental difference between expecting privacy on the Internet, and the government actively collecting all data on all people and compiling a massive database linking all of this data together.
No one should expect privacy. There are sketchy ISPs, sketchy mail providers, hosting providers, etc.
But a few hackers collecting email from a few individuals is not the same as a massive database that links everything in entire world in one nice package. A few random hackers in Russia do not have the political machinery or military machinery of the US government. They generally don't care that you're pro-gay rights (or whatever). They aren't going to try to punish you for your political views. They probably just want money or to defraud you in someway.
I also fear that the availability of such extensive records on all citizens makes it more likely that an abusive government might come to power. I.e. what Snowden referred to as 'turnkey totalitarianism'.
