Why kill a Ben sorrer umoreh for stealing according to the Gemara?

Question

In Masechet Sanhedrin daf 72a, the Gemara discusses that the Ben sorrer umoreh is judged on his Sofo, that eventually he’ll steal from his father and then come to steal from others, and because of this he’s killed. But why, according to this step by step logic that the Gemara presents, should he be killed? A normal thief only has to pay back what he stole, he never dies! And the Rambam when discussing Ben sorrer umoreh says that eventually he’ll come to kill after stealing, so accordingly it makes sense to kill him now (to prevent him from killing later where he’ll be liable to the death penalty). So why doesn’t the Gemara mention that he’ll come to kill as the final step? According to the Gemara it seems illogical to kill him now if all he’s going to do is steal

Answer 1

I would venture to explain that perhaps you are translating a word wrong in the Gemora, the words ומלסטם את הבריות this does not mean a thievery this is an armed robbery in which there are death expected. Like the Gemora in Sotah page 8B it has the same rules as if the king want to kill him. These robbers were killers, no questions about it. The Gemora in Sanhedrin you quoted was not about the stealing but about the killing. Hence we kill him “for the end” which is he is going to kill people.

Answer 2

Executing a person now for possible future crimes is a concept explicitly negated in Chazal:

According to the actions he is now doing shall he be judged and not according to what he may do in future. Because the ministering angels laid information against [Yishmael], saying, “Master of the Universe, for him whose descendants will at one time kill your children with thirst will You provide a well?” He asked them, “What is he now, righteous or wicked?” They replied to him, “Righteous.” He said to them, “According to his present deeds will I judge him.” (Genesis Rabbah 53:14).