"not for collusion, but for trying to sway the investigation."
That's what got Nixon. Not the third-rate burglary, but telling the CIA to tell the FBI to lay off.
Your overall comment is spot on. I could easily see all these guys talking to the Russians -- who were suddenly very eager to learn how an American political campaign works. They saw deals. They saw Trump Presidential Suites at the Kremlin. They saw Trump and Putin carving up the world.
They left Trump in the dark.
Then the fit slowly began to hit the shan. And Trump is frantically trying to stop it.
I remember reading a column once about how the Russian ambassador to the USA must be a remarkably bland, unassuming, faceless, shy individual who makes no impression on people. How else to explain the fact that all those Trump campaign officials and nominees for government office who simply forgot they ever met with the guy?