Amid all the lies Donald Trump has told about the Russia scandal, there is one underlying truth: The intelligence community truly fears him and considers him unfit for the presidency. This is not because the intelligence community is traitorous, or left wing, or (as Donald Trump Jr. sneeringly put it) wine-spritzer-drinking elites. It is because the IC had early access to a wide array of terrifying intelligence linking Trump and his orbit to Russia. People who spend their lives protecting their country from foreign threats saw in Trump a candidate who had at some level been compromised by one of them.
Carter Page is the kind of person who would be brought on as a foreign policy adviser only if (a) the campaign was actively seeking out Russian assets, or (b) it was so slipshod it could easily be penetrated by Russian intelligence.