The parallels between them are obvious. The two had exorbitant egos, openly admired strongmen, were obsessed with TV and had a penchant for kitsch furniture and lewd jokes. Perhaps most important, they both possessed an instinctive ability to tap into the passions of the populace. One came from real estate, the other from media: They met halfway, in the borderland of entertainment. They also shared a predilection for the politics of paranoia. Long before Mr. Trump cried “witch hunt” and labeled the Manhattan district attorney, Alvin Bragg, a “psychopath,” Mr. Berlusconi was denouncing a Communist plot brought by judges in “red robes” who were out to destroy him.

Mr. Berlusconi’s tricks and oddities to elude his critics rivaled, perhaps even exceeded, those of Mr. Trump. The hush money Mr. Trump allegedly paid to Stormy Daniels seems almost mundane compared with the time Mr. Berlusconi called the police claiming that Karima el-Mahroug, a 17-year-old guest of one of his infamous “bunga bunga” parties who had been arrested, was a niece of the former Egyptian president Hosni Mubarak. To whatever charge, Mr. Berlusconi always had an answer.

Mr. Berlusconi’s conspicuous fortune, estimated at $6.8 billion and comprising dozens of companies operating in media, finance, sports and real estate, was the bedrock of his political project. He preached his own version of the prosperity gospel, arousing hope in Italians disheartened by a corrupt political class and economic stagnation. Two decades before Mr. Trump appealed to Americans left behind by globalization, Mr. Berlusconi was capturing the imagination of the “forgotten men” of Italy by promising new jobs and tax cuts.

An oxymoronic figure, Mr. Berlusconi preached “ethical anarchy” while giving succor to the far right, tickling people’s passions with the exploits of his soccer team and surrounding himself with an ever-changing court of advisers, friends, lackeys and acolytes who hoped to take advantage of his proverbial generosity. By day, he garnered votes from the working class. At night, he invited his guests to admire an artificial volcano erupting real lapilli in the boundless garden of his oligarch-friendly, 126-room villa on the Sardinian coast.

Because Mr. Berlusconi never separated the personal from the political, his fall happened on both fronts simultaneously. Relentlessly grilled by his political opponents for trying to bend laws to his own advantage, he spiraled into an increasingly rowdy lifestyle. His name became universally associated with the sex parties he insisted on defining as “elegant dinners.” When in 2009 Mr. Berlusconi picked candidates for the European Parliament from among the female guests of these gatherings, his second wife, Veronica Lario, publicly protested against this “shamelessly tacky” behavior and filed for divorce.