Being victimized is different than being a victim. A person who is victimized is still first and foremost that same person. It is a person who has had an experience or a series of experiences, and who is likely changed as a result or these experiences, yet is not reduced down to only those experiences.
A victim becomes the experience and stays there. He begins to see all of his life through this narrow window. He attributes his feelings, thoughts, and experiences going forward to his reaction to the original victimization event. He talks about it, thinks about it, and holds on to it almost like a badge of identity. Strangely, it becomes his point of reference for his life.
So, after the buddha denies that others are the cause of one's suffering, Kassapa suggests that perhaps it's both oneself and another, but the buddha shoots down this possibility as well. The buddha is pointing to a more nuanced view regarding conditions that he shares toward the end of this exchange.
Kassapa keeps at it and then asks if suffering's arising is random and the buddha denies this is so as well. Today, there aren't that many I know of who would argue this, but there are those who speak of 'fate' and this too the buddha would deny. Fate implies that there is nothing one can do about suffering (or any other situation) because our actions do not have causal significance. Finally, a view many hold today is that suffering arises because it's the 'will of god' (or 'the gods') and the buddha again rejects this possibility because again, if it's the will of god, then there is really nothing we can do about it.
Still, the buddha teaches that though we do not bring on our suffering ourselves, nor do others, there is still something we can do in response to ameliorate suffering and even end it! This is because suffering, he says, arises based upon myriad causes and conditions (many, if not most, that we have not chosen for ourselves) and that the root cause of our suffering is ignorance.
Ignorance is generally the translation yogis use for the Sanskrit word avidya (avijjā in Pali). Avidya more literally means "not know," "not understand," or "not see." It is a cognate with the Latin vidēre ("to see") and it's echoed in the English "vision." It's the understanding that the unawakening being doesn't know nor do they see the reality of emptiness, the absence of any essential self-nature in any phenomena.
But, I also think that when we say "ignorance," we can also understand it as "ignore-once," or as we might say nowadays, "denial," because so much suffering arises through ignoring what we do not wish to acknowledge; we know it's there at one level, but choose to ignore it.
And the final point of the buddha is that because it is ignorance that is the ultimate cause of suffering and not any "individual" (which in a real sense doesn't even exist) then our focus in practice should be the removal of ignorance -- in ourselves and in others. Thich Nhat Hanh would often remind his students that "Man is not the enemy; our enemy is hatred, ignorance and fear." The bodhisattva works for the liberation of all, knowing that none can be truly free if all are not free, while knowing also that there are no 'beings' to be freed!