Elon Musk navigates between running his businesses and trying to save the planet. 

At least, he tries to draw attention to global issues which he considers urgent to tackle. 

For some time, the richest man in the world, with a net worth on paper estimated at $210 billion on May 18 by Bloomberg Billionaires Index, has been sounding the alarm about the decline of the population.  

He started by worrying about the largest historical drop in inhabitants in Japan in 2021. 

Then, instead of marveling at the beauty and history of Venice, Musk preferred to shine the spotlight on the fact that the Eternal City's population has continued to decline for years. 

For the mogul, this does not bode well for the future of Venice.

A few days after these first warning signals, Musk has just made an even more worrying announcement. The serial entrepreneur believes that it is urgent to deal with the decline in the birth rate which particularly affects rich countries and the West.

The Tesla  (TSLA) - Get Tesla Inc Report  CEO made that much clear in recent comments during a virtual appearance at the recent All-In Conference held in Miami on May 16. 

The billionaire was asked about what could be done in terms of energy production to make electricity cheaper for everyone around the world. Basically, can the electricity needs of the world's population be met at an affordable price?

"Because of just generally low birth rates almost worldwide, civilization is not headed to have a population that is an order of magnitude better than where we were kind of," Musk responded. "We're currently headed towards a population decline. And this is almost everywhere in well in the world."

Musk, who pushed the auto industry to convert to electrification in order to lessen its impact on the environment, rejects preconceived and often widely held ideas that having a child is expensive or that making the choice not to have children is because we want to save the environment.

"It basically seems as though as soon as you have like, urbanization and education beyond a certain level and income beyond a certain level, birth rates plummet. And so as countries get wealthier, their birth rates plummet," the tech tycoon said.

"It's somewhat counterintuitive, because people will say, like, well, 'it's too expensive to have a baby'. No. The wealthier they are, the fewer kids you have; the more educated you are the fewer kids you have," said the father or seven -- Y, X, Griffin, Xavier, Kai, Saxon and Damian.

He therefore argues that there are enough resources for all.

"So I'm not sure who [is going] to use all that energy unless there's a significant change in the birth rate," Musk, 50, said. "Or we have a very robot oriented economy. So that's also possible if we've got a lot of four wheeled robots in cars, humanoid robots, then you could suddenly see that there'd be perhaps a need for an order of magnitude more energy."

"But it's not coming from the humans unless something major changes on the human birth rate level. But this, by the way, is, I think, the biggest single threat to civilization right now," Musk added.

A recent study projects that the world's population will peak at 9.7 billion in 2064, before decreasing to 8.8 billion in 2100. But, if we followed the curve of the growth rate of world population, say demographers, would begin to decline around 2060.

The annual growth rate of world population was 2.1% in the 1970s. Today, this rate is only around 1%. And it should go down to 0 between 2060 and 2070, demographers say.

In her provocative book "8 Billion and Counting", political demographer Jennifer D. Sciubba says the twenty-first century is "a story about differential growth—marked by a stark divide between the world’s richest and poorest countries." 

She anticipates Europe’s population will shrink from about 521 million to about 482 million by mid-century.

In Asia, in addition to Japan, China also has the same birth rate problem.

Last January, the National Bureau of Statistics of China announced that 10.6 million children were born in 2021, down from with 12 million in 2020, despite the end of the one-child policy. This was the fifth year of decline in a row.

"Some people are thinking like having fewer kids is like better for the environment. It's just total nonsense," Musk said. "We're going to be fine even if we doubled the size of the humans. I know a lot about environmental stuff. We can't have civilization just dwindling to nothing."

"A lot of people just think that having kids is somehow bad for the environment. I want to be clear it's not. It's essential for maintaining civilization. We don't necessarily need to grow dramatically, but at least let's not gradually dwindle away until civilization ends with us all in adult diapers and in a whimper."

The world's richest man concluded by saying that he's heard many times people saying: "How can I bring a child into this terrible world?"

And his response: "Have you read history? Because let me tell you it was way worse back then."