Mr Guterres highlighted the gap between the rich and the poor in his opening speech and said a "malady of mistrust" is spreading across the globe as people strive to bring food to the table.
"I am here to sound the alarm. The world must wake up. We are on the edge of an abyss and moving in the wrong direction. Our world has never been more threatened or more divided," he said.
Although their expedition lasted only a few minutes, the trip to space in itself had cost billions of dollars. Both businessmen are eyeing to make big profits from expanding "space tourism."
During the time of rocket launches, they faced flak from critics who demanded a higher tax rate for billionaires. It was also reported that Mr Bezos, the founder of Amazon and presently the richest man on Earth, did not pay any federal income tax in 2007 and 2011.
Another billionaire Jared Isaacman led the first all-private orbital mission that returned on Saturday after three days in orbit. His flight was reportedly on a Dragon capsule and the rocket was built by Space X, the company run by fourth space-obsessed billionaire Elon Musk.
However, his ride raised more than $200mn for St Jude Children’s Research Hospital through a fundraiser where Mr Isaacman contributed $100mn and Mr Musk donated $50mn.
Looking at rising inequality, Mr Guterres added: “When parents see a future for their children that looks even bleaker than the struggles of today.”
The United Nations has pushed for space sustainability through a resolution passed last December to develop norms of behaviour in outer space.
Resolution 75/36 encouraged countries to submit their views on threats to the space system and their ideas of norms and responsible behaviours for space operations. At least 30 countries, giants in space research Russia and United States have submitted their report.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies