Washington DC - Jokes, snark, and a striking absence of sympathy have dominated public sentiment since the murder of a US health insurance executive, exposing deep frustration and anger with the nation's medical system.

UnitedHealthcare CEO Brian Thompson was gunned down by alleged shooter Luigi Mangione in Manhattan on Wednesday, setting off a nationwide manhunt before his Monday arrest in Pennsylvania.

Within moments of the news breaking, the internet erupted – not with outrage, but with cheers over the death of the 50-year-old father of two.

A Facebook post mourning his loss, shared by UnitedHealth Group, racked up more than 71,000 laugh emojis as of Friday – dwarfing other interactions before the counter was disabled.

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"My thoughts and prayers are out-of-network," became a recurring quip in comment sections, a biting nod to one notorious reason US insurance companies deny coverage – when a patient's medical provider isn't included in their plan.

Even doctors on one of the internet's largest forums for medical professionals joined the fray, posting satirical comments on the "medicine" subreddit that mimicked the jargon often found in insurance denial letters, such as "lack of prior authorization" and "failure to prove medical necessity."

Since the killing, the public has taken to venting long-standing grievances with America's privatized and exorbitantly expensive healthcare system, with some even hailing the shooter as a "folk hero."

"No one deserves this," began a TikToker, who went on to claim that the insurer delayed covering her toddler's emergency brain surgery while she was nine months pregnant and awaiting the birth of her next child.

"This isn't to condone violence – all that I'm saying is that I do not doubt for a second what the motive of that suspect was," she added.

Others fixated on the killer's looks, dubbing him the "hot assassin" or comparing him to movie stars Jake Gyllenhaal and Timothée Chalamet.

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Meanwhile, young musician Joe DeVito recently went viral with a folk song titled Deny, Defend, Depose – a rallying cry against medical corporate greed.

A New York Times report alleged that the words "delay" and "deny" – words often used by insurance companies to reject claims – were written on shell casings found at the scene of the murder.

Universal healthcare is a cornerstone of every other developed country.

In the US, however, coverage is fragmented among those with private insurance, government programs, and a sizable uninsured population.

More than a decade ago, the Affordable Care Act, commonly known as "Obamacare," addressed some of the insurance system's most anti-consumer practices – by, for instance, requiring coverage for individuals with pre-existing conditions.

However, huge gaps and deficiencies persist.

According to research and analysis group ValuePenguin, UnitedHealthcare denies about one-third of all claims, the highest rate of all insurance companies, and double the industry average.

It is also the largest US health insurer, providing coverage for around 50 million people and taking in $16.4 billion in profits in 2023, a year that Thompson was compensated more than $10 million.

The dark humor "is a coping mechanism for a population of people who feel powerless in our healthcare system," said William Flanary aka Dr Glaucomflecken, a comedian and ophthalmologist who does popular medical satire skits.