Leo, originally from Chicago, also spoke about the United Nations, his decades working as a missionary in Peru, how he has been adapting to the role of pope, and his hopes for peace in the bloody, three-year conflict between Ukraine and Russia.
He has shown a more reserved style than his predecessor Pope Francis, who often gave interviews, and prefers to speak from prepared texts. Sunday's excerpts were released on the Catholic news site Crux.
"CEOs that 60 years ago might have been making four to six times more than what the workers are receiving … 600 times more (now)," Leo said in the interview, conducted at the end of July for a coming biography.
"Yesterday (there was) the news that Elon Musk is going to be the first trillionaire in the world," he said, discussing Tesla's $US1 trillion ($A1.5 trillion) compensation plan.
"What does that mean and what's that about? If that is the only thing that has value anymore, then we're in big trouble."
Leo, elected the first US pope by the world's cardinals in May to replace Francis, criticised the UN as no longer being able to foster effective multilateral diplomacy.
"The United Nations should be the place where many … issues are dealt with," said Leo.
"Unfortunately, it seems to be generally recognised that the United Nations, at least at this moment in time, has lost its ability to bring people together on multilateral issues."
On becoming pope, Leo said he felt more prepared at first to lead the world's 1.4 billion Catholics on spiritual matters but less prepared to play a major role on the global diplomatic stage.
"The totally new aspect to this job is being thrown onto the level of world leader," said the pope.
"I'm learning a lot and feeling very challenged, but not overwhelmed. On that one I had to jump in on the deep end of the pool very quickly."
