There seems to be two main ideas here. I'll address them one by one.
First, the notion of 'evil', or, the wish to gain in expense of others. In older times we call this greed, though applied via your lens it assumes a zero-sum game where one's gain must necessarily result in the loss of another. Quite a lot of debate is still raging on about whether human society is a zero sum or positive sum game, and though I agree with the latter, I'll humour your assumption and go on with the argument.
If we were to assume human society is a zero-sum game, and that such 'evil' as you've mentioned would require the prefixing of Bezmenov's subversion techniques with powers political, then it would indeed seem that simply knowing the opponent's moves is not enough - after all, as you've said, a weakling would find little comfort in knowing the blow is going to land on his shoulder instead of his abdomen. The reality, however, is that the modus operandi of subversion lies not in direct blows as you've described. Rather than direct assertions of political power, it is the psychological response of the targeted society that is of the essence. Political clout helps in administering subversion, but it is absolutely not needed. What is needed is the response from the populace.
From Yuri's example we see the fiercest progenitors of subversion not being foreign agents, but local sympathisers of the foreign ideology. These would be, in Hong Kong's case, people like professors who hold an idealistic understanding of communism, politicians who truly believe Hong Kong can help China to democratise, and those people who think China means us well, arriving at such conclusions either out of ignorance or influenced by propaganda. It is because Hong Kong is a ideologically "democratic" society --- that is, the people of Hong Kong are allowed to hold a variety of opinions --- that naturally such thoughts and people may emerge. The role of the subverter, then, is not to invent such thoughts ex nihilo, but instead to shape and help such anti-Hong Kong thoughts and ideologies to fester and grow.
It is due to the above that the "weakling dreading the next blow in the boxing ring" metaphor doesn't work, for the damage comes not from the foreign enemy's direct blows, but from the target's own limbs. Imagine it being less of a boxing match, and more of the kind of martial arts as judo, or tai chi --- the more you react bluntly, the more damage is reflected back to you. Such is the case in subversion. It is a method of psychological warfare, and it depends on uneducated, emotional, blunt responses to attempts of subversion in order to succeed.
It is precisely because that the aim of subversion is that of an emotional, psychological response that we, as the ones being attacked, miraculously do not need political power to defend ourselves. If anything, fighting back with direct political force will only worsen the situation, and bring us closer to the Crisis point where civil war breaks out (which the subverter enemy would like to see, as it further weakens the nation). That is why I've been emphasising the psychological nature of subversion, and hence the psychological nature of defence as a result.
The second idea you've presented seems to be the problem of eternal struggle between those who have and those who have not. Again, if we were to assume human society is a positive-sum game, then this problem will simply dissolve. It would also be a non-issue if we don't apply this overly crude understanding of society as polarising sides of either have's or have-not's. In fact it's a very Neo-Marxist understanding that pits everyone in either of two extremes in a re-purposed form of class struggle... I myself vehemently hates anything that is born of Marxism for its crudeness so I probably will just tell you to get lost if that's the thrust you're aiming for.