True or false, philosophically, bomber pilots, serial killers and executioners are the same in the sense?

False. You are making a false assumption that bomber pilots and executioners automatically consider killing fun. That is an illogical assumption, end of argument. Perhaps there are even some serial killers who do not find it fun either and they are driven by some other motivation. I also doubt that you are qualified to judge US foreign policy from a position of knowledge instead of mere and rather trivial opinion.