The precepts are there to keep you from creating the kind of bad kamma that will cause bad things to happen to you. In this way, you protect yourself as you protect others.

"We were talking a while back about the precept against killing and someone said, “Well, I guess the Buddha made this precept because life is sacred.” And I said, “No. No, the Buddha never said life is sacred.” That idea came from wanting to understand the precepts without ever having to think about kamma. Kamma underlies everything the Buddha taught. Virtue, concentration, discernment: These things are all kamma. The path is a kind of kamma. And you have to understand it that way. As for the rationale behind the precepts, as the Buddha said, “Do you want to be killed? Do you want to have people steal your things? Do you want to have people have illicit sex with people who are dear to you? Do you want to be lied to? Do you want to live in a society where people are drunk?” “Well, No.” “Well, then don’t do those things.” “Do you like to be spoken to in a harsh and malicious way?” “No.” “Then don’t go do those things.” The precepts are there to keep you from creating the kind of bad kamma that will cause bad things to happen to you. In this way, you protect yourself as you protect others."

~ Thanissaro Bhikkhu "Put the Other Person’s Heart in Yours"