This might be a reasonable argument if there was any direct evidence that all of the billions spent on "collecting it all" had lead to the actual discovery of a

This might be a reasonable argument if there was any direct evidence that all of the billions spent on "collecting it all" had lead to the actual discovery of any plots that would not have been found by other means. But, as with "enhanced interrogation", I am not aware of any credible evidence to that effect, despite the incredible incentive for the government to manufacture some. We knew about the 9/11 attackers before their attack, but failed to put that information to good use. Trying to know everything does not work. Targeted, traditional police investigation works. Money diverted from the latter to the former is wasted and reduces safety.