It's a red herring whether what Mangione did (who as I've said previously seems to be politically incoherent) is "good" or "evil". You can't so easily extrapolate from such a judgement to a politics, even if because he's photogenic he's becoming a lightning rod for mass resentment of the health system.
Instead, it's more about how we choose to explain for ourselves why anyone would get upset about a CEO taking a bullet, supposing they then tacitly accept the same CEO's company denying its customers life-saving treatments at the highest rate in its industry and thereby hastening the deaths of thousands.
The sarcasm of "because life isn't fair" amounts to a reactionary doubling down on these failures. There's no utopianism when the US implementing similar systems to those which exist in most other OECD nations would be a big improvement.