Why does it make us feel better if we put a vicious criminal to death, as opposed to imprisoning him for life?

Because the longer they are in prison, the longer people like you and i have our taxes go towards feeding them, powering their TV, keeping them able to exercise, read ect. And it over crowds our prisons (Which Dems complain about all the time)If they are in prison for life, then they must have committed a crime that takes away their right to life. So what's the point of keeping them imprisoned until they die, when someone can end it all for them, and save us money, and space.