> Since about the 1960s, most of the damaging spies have been in it for the money, not ideology.

That isn't true as a general statement. It is true that American's in particular are generally more open to the money than other motivators compared to other nationalities, but these differences are not that large and are very much based on the individual, so no real general statements can be made. Romeos and Ideology have played a big part in espionage and subversion over the years equally if not moreso.

Mccarthyism was a response to a growing threat, one that has not subsided over the years. Those that lived through, or participated in some of these events often saw a correlation between the adoption of the elements derived from Marxism and its relatives, albeit they are almost always obscured by intention; and the progressing ruin of individual life and western society at the broad scales.

Subversion works insofar as it is sufficient to cause regime change when you are unable to respond to it or stop it as a society. The next generation doesn't know any better and are developmentally vulnerable to such overtures. They lack the discernment to catch sophisticated lies and liars, and before they know it themselves they've joined the cause as an adversary.

If you are interested in detailed accounts from this time period, and more specifically part of what prompted these movements. There's two books that are particularly good that cover in detail with regards to the East German Stasi which operated during this time frame internationally in conjunction with other red perils (Russia/China) often with terroristic aims.

The first is written by an American, John O. Koehler "Stasi, the Untold Story of The East German Secret Police". The second is written by Markus Wolfe, who was a Spymaster for the Stasi, and it is called, "The man without a face".

Both are particularly good as resources, and cover the time period in the various perspectives up until the fall of the Berlin Wall in the 90s (starting late 1989).

The threats which sparked McCarthyism are still threats today and haven't diminished, in many respects they've increased with the level of technology, and progression of the related sciences, exponentially, but this type of threat is a cursed problem for open societies.

There are many ways subversives can effectively brain wash the unsuspecting, induce delusional or schizophrenic-like behavior, and agitate others indirectly towards sedition and treason. Few working adults today are prepared sufficiently to recognize or defend themselves against many of these threats.