I enjoy fantasizing about executing really bad people such as murderers, child abusers, rapists, and terrorists.
I really hope you're joking about enjoying fantasizing about it. Why would you enjoy that?
I feel that all life is precious, so some people deserve to have it taken away from them
It's okay to want serious criminals to face justice, but this needs to be done legally.  If you keep fantasizing about killing people, you could end up having the same thoughts as real-life murderers have.
Choosing capital punishment over life imprisonment is a valid alternative to making murderers pay for their crimes.
You're correct in thinking that some murderers can be sentenced to death in some place, but that's up to a court of law. Civilians can't just execute someone on their own, and fantasizing about it isn't normal.