It's a war, the other side fights back. You win some and you lose some, and some are rained out. There is heroism and incompetence on both sides. In free societies we fight with one hand tied behind our back. In totalitarian societies, a huge proportion of their population defects, at great peril to themselves. And on both sides, there is the great friction of bureaucracy, because more than anything, espionage is mostly about data processing, not acquisition. Most spies clip articles out of newspapers and try to fit them into a pattern.

Revisit this thread after you've finished watching those Le Carre videos. He used to be an intelligence officer. He says they are not autobiographical, but I bet they have a great insight into that world.