You read stories of ones who were caught, and you cannot make it it up. Their main recruitment target are idiots in places of high power.
KGB recruited more agents than real spies. They had many more people doing lobbying, covert propaganda, and subversion, than peeking into Western secrets.
They really valued their high profile spies, but their influence agents — "pomogaikas" were near disposable. Finding idiots in places of power was always easier than finding smart, ideologically motivated betrayers fit for espionage assignents.