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The argument could be made, not that I concur with my fore-poster, that they (if we set aside that they are in chains or assume the chains to be inflicted on themselves) are responsible for their own demise.
If I recollect correctly Plato also considered that they may even kill the truth-teller for telling the truth after he saw the light, just because they do not believe him and think he's crazy.
That's quite heavy, I reckon, for how do you want to help them without showing them the truth and not letting them live a lie? As to someone who has seen the light it is obviously a must to lead the non-seeing onto the right path.