There's a difference, though, between 'spies' and fifth-columnists. That is, between people who pass on valuable information and those with power in a nation whose actions are intended to serve the interests of a foreign nation.
Furthermore, I think for the latter category it's a blurry line between those whose motivation is explicitly to aid that foreign country and those who just happen to have a self-interest that partially coincides with those of that country. Which brings it back to the German dependence on Russian gas supplies.
Trying to connect it to the simple transactional case of 'spies' being paid for information, seems to be over-simplifying the situation, to me.
In much the same way that conspiracy-theorists do - when they conclude that political outcomes must be the results of explict conspiracies organised consciously, rather than the concequences of different groups each pursing their self-interests.