Nixon was caught because he taped himself obstructing justice. Manafort was caught because he emailed incriminating documents in the clear. How the hell are we going to catch criminals who somehow avoid doing monumentally stupid things?
I think the problem is not as big because you don't need to have those people do monumentally stupid things all the time. It's sufficient if they do it every so often. And unless someone is an incredibly paranoid person which has the privacy routines ingrained in their DNA, everyone does make stupid mistakes every once in a while.
https://www.cnn.com/2013/10/04/world/americas/silk-road-ross...