"Winners Take All" author Anand Giridharadas has emerged as an outspoken critic of the elite and a champion of progressive politicians.

He believes that America's most pressing problem is its wide inequality, and that potential presidential candidates Howard Schultz and Michael Bloomberg would be unwilling to make necessary changes like significantly increasing taxes on the rich.

This article is part of Business Insider's ongoing series on Better Capitalism.

Since former Starbucks chairman Howard Schultz announced that he's considering a centrist, independent run for president of the United States, the growing populist resentment of billionaires like Schultz (who prefers the label "person of means") has bubbled to the surface.

For Anand Giridharadas, author of "Winners Take All," Schultz — along with former New York City mayor and fellow billionaire businessman Michael Bloomberg, who is also considering a run as a Democrat — has shown why we don't need a billionaire president to replace the one we already have.

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In a recent interview with Business Insider, Giridharadas said their performance so far — like the way Schultz has dismissed progressive tax proposals like Rep. Alexandria Ocasio-Cortez's call for a 70% marginal rate on income above $10 million as "un-American" and how Bloomberg said that Sen. Elizabeth Warren's proposed 3% wealth tax for fortunes above $1 billion was "unconstitutional" and would lead to lead to chaos like in socialist Venezuela — proves that even if they earnestly want to "do good," they're reluctant to make structural changes the US needs.

"These old billionaire, encrusted oligarchs are really showing their terror," Giridharadas said. He believes that income and wealth inequality has hampered American growth — which Fed chairman Jerome Powell has also stated — and that to correct it, the country's wealthiest are going to have to lose some of their influence over society.

"For the first time in my lifetime, we're talking about whether billionaires should be able to be here, and I think my message to these guys is, you are free to go," he said. "If you think it's confiscatory to have a 3% wealth tax, you're absolutely free to go."

Read More: Wealthy investor Nick Hanauer says the US economy mints billionaires while many Americans are struggling, and there's no excuse for it

Wealthy Seattle-based venture capitalist and progressive activist Nick Hanauer knows, respects, and likes Schultz, but agrees with Giridharadas' main point. "I just do not believe that the country at this point needs what Howard thinks of as, I think they call it 'centrism,' which basically in the Democratic party is straight-up trickle-down economics but without the racism," Hanauer said on his podcast, "Pitchfork Economics."

And, as a collection of polls has shown, the majority of Americans are in favor of increasing taxes on the rich, and are in favor of the proposals Warren has proposed as presidential candidate, which she drew up along with University of California Berkeley economists Emmanuel Saez and Gabriel Zucman.

"The kind of change I'm talking about sounds scary to people, but it should only really sound scary to a very few people, who have been profiting from an unfair system," Giridharadas said. "They are scared that people now realize that America actually doesn't have to be run for billionaires' benefit. What is actually un-American, to use Howard Schultz's term, is an America run for the few. That's not the promise on which this country was founded."