Brian Thompson was uniquely unsympathetic. he wasn't well-known, his wife had separated from him, and nearly everyone has a personal experience of some family member being fucked over by health insurance, with UnitedHealth being especially heinous. the media really struggled to find anyone to say sincerely positive things about him. he really was the best possible target Luigi could have chosen.
I agree he was unsympathetic but there are far far "better targets" (your words) for vigilante murder if public opinion is the bar. Robert Richards IV is one of my go to examples for the complete lack of justice for the hyperwealthy [1] but there are mountains of big pharma, big food, insurance, church leaders, and private military people who are absolute monsters by any reasonable standard.
I think Brian Thompson was a fuckface (and all the others who help enable the evils there in the name of profit) but he was basically doing what America has deemed not only fine but noble - make as much money as possible without fully breaking the law (or, more accurately, being forced to stop by the law - many routinely and intentionally break the law in their pursuit). Half the country loves and celebrates this behavior to the point where politicians _brag_ about how good they are at it.
