it seems that it's not as if I'm making the world a better place, I'm just putting myself in a better world.

It seems like you are not making world a better place because you think about fixed probability of becoming a murderer, which your decisions cannot change. But the probability of you becoming a murderer is a result of your decisions.

You have reversed the causality, because you imagine the probability of you ever being a murderer as something that existed sooner, and your decisions about murdering as something that happens later.

You treat probability of something happening in future as a fact that happened in the past. (Which is a common error. When humans talk about "outside of time", they always imagine it in the past. No, the past is not outside of time; it is a part of time.)