In 1992, billionaire industrialist David Koch was diagnosed with advanced prostate cancer and given just a few years to live. Thanks to his enormous wealth, he was able to purchase the best treatment in the world, and he survived 27 more years until his death last week.

For all his adult life, he’d led Koch Industries, a diversified manufacturing conglomerate, with his older brother Charles. Now taking in around $110bn per year, the company creates chemicals and fertilizers; it produces synthetic materials such as Lycra; it sells lumber and churns out paper and glass products; it makes electronics components used in weapons systems. But first and foremost, Koch Industries mines and refines petroleum and operates pipelines to spread it throughout North America.

Koch Industries, a private company, is the United States’ 17th-largest producer of greenhouse gases and the 13th-biggest water polluter, according to research from the University of Massachusetts Amherst – ahead of oil giants Exxon Mobil, Occidental Petroleum and Phillips 66. The conglomerate has committed hundreds of environmental, workplace safety, labor and other violations. It allegedly stole oil from Indian reservations, won business in foreign countries with bribery, and one of its crumbling butane pipelines killed two teenagers, resulting in a nearly $300m wrongful death settlement. The dangerous methane leakage, carbon emissions, chemical spills and other environmental injustices enacted by Koch’s companies have imperiled the planet and allegedly brought cancer to many people. But it took Koch’s own struggle with the disease for him to care about cancer and fund research to combat it.

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This is the tragic mindset of many a rightwing oligarch: The toils, the woes, the maladies of humankind are irrelevant – unless they happen to me, or perhaps my close family members. I’ve never struggled to live on $7.25 per hour, so why is it a problem? An ailment has never caused me to go bankrupt, so why would anyone possibly need government subsidies to pay for life-saving medical care? Climate change has never directly affected my life so I’ll keep on denying that humans have anything to do with it. Even though I inherited a business and a fortune, I earned every cent of my astronomical net worth. If you worked as hard as I have, you would have what I have, too.

Koch epitomized this grotesquely selfish mentality during his 1980 vice presidential campaign on the Libertarian ticket, when he ran on abolishing Social Security, Medicare and Medicaid, welfare benefits, the minimum wage and the Environmental Protection Agency. He put $2m of his own money into the effort and campaigned to ax all campaign finance laws so he and his brother could maximize their bloated political influence without any pesky rules attempting to honor the constitutional premise of American elections: “One person, one vote.”

It is this cruel mindset that was the real cancer plaguing David Koch. It wouldn’t kill him, but it would spread itself into university curricula, the halls of Congress, regulatory agencies, and the White House. It possessed the unfathomably rich who came before him, and it will infect the opulent oligarchs who come after him. It is the cult of anarcho-capitalism, the faithful worship of the divine free market that has shined so brightly on Koch and his family. If only we could do away with government altogether, we’d become a true utopian society: a handful of corporate monarchs ruling over billions of wretched serfs who toil away until their deaths, faithfully adding zeros to the quarterly revenues of the select few at their own fatal expense.

Not only did Koch help unleash countless metric tons of greenhouse gases from the earth, he was a key funder of climate change denialism, stiff-arming scientists in order to further plunder the earth he was destroying. Revelations in Christopher Leonard’s new book, Kochland, show that Koch played an even greater role in funding climate change denialism than we previously knew. As we careen towards a climate catastrophe that seems more and more likely to happen within the next 11 years, we can rightly pin a portion of the blame on David and his brother.

With Charles, David funded and participated in a network of free-market thinktanks that produced academic literature in support of slashing taxes and gutting regulations in order to aid mega-corporations like Koch Industries. These ideological centers include the Cato Institute, which the Kochs founded and where David was a longtime board member; the American Enterprise Institute, where he was a member of its National Council; George Mason University’s Mercatus Center and the Institute for Humane Studies; and the Heritage Foundation. Now alumni of the Koch academic and policy network have become government administrators, regulatory officials, political advisers and lifetime judges.

In 1984, David co-founded the predecessor to the non-profit Americans for Prosperity (AFP), among the first of many political major groups the brothers would fund and operate. The Kochs increased their political spending and engagement over decades, using AFP and other groups to publicize the thinktanks’ laissez-faire policy proposals and pressure members of Congress to support them. In 2009, AFP helped get the allegedly grassroots Tea Party off the ground, as it and other Koch network organizations began years of campaigning against President Obama’s effort to give millions of low-income Americans health insurance and expanded Medicaid. David has funded research into cancer therapies but appears to believe that only the financially secure deserve treatment.

Spending by the Kochs’ political groups and campaign donations from the Kochs and their company’s Pac made a wave of rightwing ideologues into lawmakers at the state and federal levels. The Tea Party sweep in 2010, a phenomenon that laid the groundwork for a rightwing nationalist president, would not have been nearly what it was without the Koch largesse. Now the Koch political network claims to be distressed at President Trump’s cruel immigration policies and tariff wars, yet the network championed the contemporary far-right movement that has seated countless lawmakers who revel in anti-immigrant and nationalist policymaking.

In the current decade, while Koch-backed state legislators made sweetheart deals with oil and gas companies and crippled the progress of solar companies, Koch beneficiaries in the House and Senate were cutting taxes, undoing federal regulations, and doing all they could to kick millions of Americans off of their health care coverage.

When you walk around Cambridge, Massachusetts, you’ll pass by MIT’s David H Koch Institute for Integrative Cancer Research or the David H Koch Childcare Center. When taking in upper-crust Manhattan arts and culture, you’ll come across Lincoln Center’s David H Koch Theater. For those who don’t know about Koch’s business and political operations, he must seem like a generous man.

The directors of these institutions are ever grateful to Koch.

“David Koch was a model philanthropist who funded initiatives across a swath of cultural, scientific, and medical institutions,” Robert Millard, chair of the MIT Corporation, said in MIT News. “His generosity has benefited humanity broadly – from the arts to cancer research to science. MIT is deeply thankful for his many contributions to our community.”

“His contributions to medical research will live on forever; they have and will continue to benefit millions of Americans and others around the world,” said Jonathan Simons, CEO of the Prostate Cancer Foundation, in a tribute to Koch. “We will miss his sense of humor, his wisdom and his insightfulness.”

Koch may have kept some arts institutions on life support, bolstered the Natural History Museum’s dinosaur exhibition, or employed cancer researchers, but we must not let these philanthropic acts cover for a billionaire whose corporate greed has gravely endangered the future of the planet and the human species. This is the point of these seemingly magnanimous contributions: to cast the Kochs in a positive light, deflecting criticism of Koch Industries’ shameful business practices and defending the legacy of a heartless robber baron.

What was the prime motivator behind the life and career of Koch, an MIT-educated chemical engineer who denied the existence, and the harms, of man-made climate change? Was it his extreme distaste for authority, birthed during his youth under a strict, Nazi-supporting nanny and an often absent father? Was it a religious commitment to free-market capitalism and an honest belief that the market, if truly unfettered, will solve every daunting problem for humanity? Was it a sincere belief that, although he and his brother were born to a wealthy oil executive, every single poor and working-class person could pull themselves up from nothing, with no help from anyone, in a drastically unequal society, if they just tried harder?

I don’t think it was any of these explanations. The answer is very simple. It was greed, the blind pursuit of horrifying wealth and power. An addiction that has left the country less equal and the planet endangered.

David Koch died as the eleventh-richest man in the world, with an estimated net worth of $51bn. His name is plastered on the facades of New England cancer centers and Manhattan hospitals and performance halls. But these historical imprints are temporary and relatively inconsequential compared to his lasting legacy, something far more significant, and terrifying. Koch’s never-ending quest for obscene wealth no matter the consequence – and that of his brother, his fellow oligarchs and his political allies – will be part of every future climate change-intensified weather disaster; every city undone by catastrophic sea level rise; every animal species that goes extinct because of warmer waters, desertification, or biblical floods; and every desperate climate refugee.

Death and destruction. That is David Koch’s legacy.