I live in a country where people were chanting and raising their fists in 2016 when then candidate Rodrigo Duterte promised the people he will turn Manila Bay red, with the blood of people he will kill. People clapped and cheered this. Most responses in favor of this - comes from a victim mindset. Like if you were the son or family member of a victim. That said, the topic is multi-faceted. A huge part of it deeply personal. If you come from a spiritual and religious perspective, and read the part where God was bringing judgment on Cain, God gave him a mark - that is, the Mark of Cain, that forbade other people from seeking retribution. In predominantly Muslim South of our country, there is such a thing as a "rido" or clan wars. Where tribes or communities, perform revenge killings often to such extent that both sides are almost extinguished.