Satan is the opposite of God and is the prince of nothingness. These people are totally devoted to Satan, and that is why nothingness, non-existence and emptiness appeal to them so.
Yes. Have you noticed how these people actually enjoy empty lives? fertile ground for the devil.
Yes. Precisely so.
Singer says: “I do think it would be wrong to choose the non-sentient universe.” But he can't tell you why, because the moment he takes his own argument to the next step not only does he have nothing in common with the Benatars of the world, he no longer even has anything in common with his old self anymore. He can't answer that question and remain who he has been until now.