If Mitt Romney’s association with Bain Capital ends up sinking his presidential campaign, he’s unlikely to appreciate the irony. But, if he needs consolation, he might consider seeking solace in American history. The fact is that no successful businessman has ever been a successful president, and only a few have even been serious contenders for the job.

This might seem odd, given Americans’ long romance with wealthy entrepreneurs and the enterprises they build. But a talent for developing private companies and making big profits seldom translates into wooing a majority of voters or governing a contentious republic. It may, in fact, blind one from recognizing critical differences between those equally difficult endeavors.

The most famous example of this disconnect was Herbert Hoover—a multi-millionaire who, like Romney, believed that America needed a shrewd capitalist at the helm of state. By the age of forty, the dour Quaker from rural Iowa had made a sizeable fortune as a metal engineer and developer of mines in several foreign countries. During World War I, Hoover employed his skills for a large, humanitarian purpose, arranging for food to be funneled to the millions of Europeans impoverished by the war. Then, in the 1920s, he became a high-profile Commerce Secretary, bringing industries together in trade associations where they could regulate themselves. Thus, Hoover had gained fame as an unelected public servant as well as one of the richest businessmen of his day—in contrast with William Randolph Hearst and Henry Ford, self-serving contemporaries who had earlier flirted with presidential runs.

When he ascended to the White House in 1929, many commentators expected that Hoover’s organizational acumen would make him a brilliant, practical leader. “We were in a mood for magic,” recalled one journalist about the start of his presidential term, “We summoned a great engineer to solve our problems for us; now we sat back comfortably and confidently to watch the problems being solved.”

But the onset of the Great Depression later that fall required the skills of a master politician, and Hoover, who had never run for office before, proved to be a less-than-mediocre one. A stiff and awkward speaker, he neither showed empathy for the jobless nor rallied Congress behind a credible plan to reverse the nation’s economic slide. Hoover’s stern belief in “rugged individualism” had helped win him riches and renown. But it prevented him from recognizing that Americans in trouble needed material relief instead of sermons about the evils of the dole and an unbalanced budget. “The Great Humanitarian who had fed the starving Belgians in 1914, the Great Engineer so hopefully elevated to the presidency in 1928, now appeared as the Great Scrooge,” writes one historian. After a career spent commanding his own organizations, Hoover was unable to adjust to a job that required persuasion, adaptation, and compromise.