Mark David Chapman killed John Lennon because he was famous and people admired him. Chapman was jealous of Lennon’s popularity, talent and success. Chapman was a loser without talent who fancied himself more talented than Lennon.
Andrew Cunanan was similar to Chapman in that he also wanted to be wealthy and famous without having to exert any effort or develop talent. He was also jealous of the people he killed .
Both killers were prolific liars who pretended to have more money and material wealth than others. Chapman pretended to be a wealthy art collector. Both were often in debt to other people. Neither had met any goals related to education or career development.
OTOH, Mangione was someone who had wealth of his own, but lived somewhat frugally. He completed a quality education, with honors and accomplishments and worked hard at his career in spite of his poor health.
Unlike Chapman and Cunanan, he had no aspirations to be like his victim. He wasn’t jealous of Thompson’s talents, but felt he was using his skills to harm innocent people. Mangione didn’t aspire to work for the insurance industry. He had friends and colleagues and was respected and liked by his peers.
Lucas Mangione had nothing in common with Chapman or Cunanan. The motives behind the murders they committed were different.