Depends.
I have never killed or had anyone killed.
I have however hurt someone who was trying to mug me. And I hurt him a bunch.
Also have friends who have killed people in combat in service of their oath to the Constitution. Not an easy thing, and it does give some of them nightmares.
But killing people for personal benefit? There is a word for that: EVIL. And such does come with a cost.
We have our own Richard III in the Clintons
"I must be married to my brother’s daughter, Or else my kingdom stands on brittle glass. Murder her brothers, and then marry her— Uncertain way of gain. But I am in So far in blood that sin will pluck on sin."
Will we ever see our battle on Bosworth Field?