The difference is self defense. As stated elsewhere in this thread, we should all agree its morally acceptable to kill nazis. With them, it's either kill or be killed. If we didn't step up against them in WW2 it would have been disastrous. And with CEOs, billionaires, and other business execs it's no different. They're actively killing everyone they can as quickly as they can because it makes them a quick buck.

So ultimately it boils down to self defense.

A state however gets no self defense out of capital punishment. It instead becomes a way to silence political opponents, innocents routinely are executed, and so on. The state cannot be granted the power to kill because it will abuse it. The people eventually need to defend themselves from the state when it is granted this power.