There have been several public opinion polls that included questions about Luigi Mangione. He’s consistently unpopular among the average population and his actions are generally unsupported. Not at all surprising for an extremist activist who literally committed murder in public.
It’s only when you visit smaller internet bubbles like Reddit where you can start to get into areas where it feels like his actions are widely supported.
A lot of activists are like this: If you go into little bubbles that align with their actions they seem popular. Zoom out and look at the population, including people they were trying to persuade and reach, and they’re not popular like they seem within the bubble.