According to the March 2017 article in the New Yorker by Jane Mayer (also the scourge of the Koch brothers):
During Bill Clinton’s Presidency... Mercer insisted at a staff luncheon that Clinton had participated in a secret drug-running scheme with the C.I.A. The plot supposedly operated out of an airport in Mena, Arkansas. “Bob told me he believed that the Clintons were involved in murders connected to it,” Patterson said...
Two other sources told me that, in recent years, they had heard Mercer claim that the Clintons have had opponents murdered.
...Mercer arguing that, during the Gulf War, the U.S. should simply have taken Iraq’s oil, “since it was there.”
...Mercer, speaking of the atomic bombs that the U.S. dropped on Hiroshima and Nagasaki, argued that, outside of the immediate blast zones, the radiation actually made Japanese citizens healthier.
...Mercer, for his part, has argued that the Civil Rights Act, in 1964, was a major mistake. According to the onetime Renaissance employee, Mercer has asserted repeatedly that African-Americans were better off economically before the civil-rights movement. (Few scholars agree.)
...Mercer proclaim(ed) that there are no white racists in America today, only black racists.
...Mercer said that concerns about (global warming) were overblown. After Patterson shared with him a scientific paper on the subject, Mercer and his brother, Randall, who also worked at the hedge fund, sent him a paper by a scientist named Arthur Robinson, who is a biochemist, not a climate expert. “It looked like a scientific paper, but it was completely loaded with selective and biased information,” Patterson recalled. The paper argued that, if climate change were real, future generations would “enjoy an Earth with far more plant and animal life.”
...Mercer’s political opinions “show contempt for the social safety net that he doesn’t need, but many Americans do.” He also said that Mercer wants the U.S. government to be “shrunk down to the size of a pinhead.”
Several former colleagues of Mercer’s said that his views are akin to Objectivism, the philosophy of Ayn Rand. Magerman told me, “Bob believes that human beings have no inherent value other than how much money they make. A cat has value, he’s said, because it provides pleasure to humans. But if someone is on welfare they have negative value. If he earns a thousand times more than a schoolteacher, then he’s a thousand times more valuable.”
...Another former high-level Renaissance employee said, “Bob thinks the less government the better. He’s happy if people don’t trust the government. And if the President’s a bozo? He’s fine with that. He wants it to all fall down.”
The notion that Mercer is fine if the government fell down makes him the perfect donor for Trump, and that is what he is.
I was surprised that Mercer wasn't quoted as actually being a devotee of Ayn Rand since his views align perfectly with hers.
And of course we can blame the ability of the Mercers to do so much evil on Citizens United. As the article notes:
After the Citizens United decision, in 2010, the Mercers were among the first people to take advantage of the opportunity to spend more money on politics.
The Mercers, being a bunch of nuts, of course support other nuts besides Trump:
DeFazio’s Republican opponent was Arthur Robinson—the biochemist, sheep rancher, and climate-change denialist. The Mercers became his devoted supporters after reading Access to Energy, an offbeat scientific newsletter that he writes. The family has given at least $1.6 million in donations to Robinson’s Oregon Institute of Science and Medicine. Some of the money was used to buy freezers in which Robinson is storing some fourteen thousand samples of human urine. Robinson has said that, by studying the urine, he will find new ways of extending the human life span.
And of course the Mercers are in league with the Kochs. At least the Koch brothers will have company when going down in history as the people most responsible for killing the planet with their science denialism and money.
By 2011, the Mercers had joined forces with Charles and David Koch, who own Koch Industries, and who have run a powerful political machine for decades. The Mercers attended the Kochs’ semiannual seminars, which provide a structure for right-wing millionaires looking for effective ways to channel their cash. The Mercers admired the savviness of the Kochs’ plan, which called for attendees to pool their contributions in a fund run by Koch operatives. The fund would strategically deploy the money in races across the country, although, at the time, the Kochs’ chief aim was to defeat Barack Obama in 2012. The Kochs will not reveal the identities of their donors, or the size of contributions, but the Mercers reportedly began giving at least a million dollars a year to the Kochs’ fund. Eventually, they contributed more than twenty-five million.Possibly the biggest monster in the Mercer family is Robert's daughter Rebekah and her ties to the neo-Nazi monstrosity Breitbart:
Rebekah Mercer is highly engaged with Breitbart’s content. An insider there said, “She reads every story, and calls when there are grammatical errors or typos.” Though she doesn’t dictate a political line to the editors, she often points out areas of coverage that she thinks require more attention. Her views about the Washington establishment, including the Republican leadership, are scathing. “She was at the avant-garde of shuttering both political parties,” the insider at Breitbart said. “She went a long way toward the redefinition of American politics."