There have been situations when I was attacked in the past, where I felt the attack was without justice, that I had been harmed and that I was blameless. But perhaps precisely because of my innocence, my response was self-righteous and proud. I egotistically 'took on' the opposition, and became increasingly angry and vengeful.
The question of whether such a response is 'effective' in the real world then becomes irrelevant - because one has been corrupted.
I have experienced this in myself - and I have seen it in others - many others over the years. When somebody has been genuinely wronged and they are genuinely innocent, it is a special hazard - or so it seems to me. Such people may destroy their own lives in bitterness and resentment; and are very resistant to repentance because they feel themselves so much 'in the right' and therefore regard any attempt to help them 'move on' as taking sides against them.
This is an absolute tragedy, a waste of a mortal life, when a person will not let go of his or her grievances (against a parent, spouse, nation, race, bigot or whatever). Whether or not the grievances are 'legitimate' this strikes me as one of the commonest and deepest sins among older people - even without encouragement - but of course this is a sin which is encouraged by our culture of resentment and victim groups.
Note: As CS Lewis also said somewhere, on the other side of the coin: it is a grievous thing when one's own selfish, spiteful or simply careless actions have led to this sin in others - and may well have happened without one's knowledge.