Amazon boss Jeff Bezos is the richest person in the world with a current net worth of $125 billion, according to the Bloomberg Billionaire Index. And he's investing much of his Amazon fortune in the development of space technologies through his aerospace company Blue Origin.

Why? "Because I think it's important," Bezos tells Norah O'Donnell of "CBS Evening News" in an interview which aired Tuesday. "I think it is important for this planet. I think it's important for the dynamism of future generations. It is something I care deeply about. And it is something I have been thinking about all my life."

Bezos — who says "you don't choose your passions, your passions choose you" — became fascinated with space when he was a child watching astronauts Buzz Aldrin and Neil Armstrong land on the moon, he tells O'Donnell.

TWEET: CBS NEWS EXCLUSIVE: @JeffBezos wants his space tourism company Blue Origin to be "an instrumental part" of an American return to the Moon; alongside Amb. Caroline Kennedy, he tells @NorahODonnell that space exploration is critical to our survival.

Further, developing space technologies is critical for human beings to have a long future, Bezos says.

"We humans have to go to space if we are going to continue to have a thriving civilization," Bezos says. "We have become big as a population, as a species, and this planet is relatively small. We see it in things like climate change and pollution and heavy industry. We are in the process of destroying this planet. And we have sent robotic probes to every planet in the solar system — this is the good one. So, we have to preserve this planet."

To do that will require being able to live and work in space, says Bezos.

"We send things up into space, but they are all made on Earth. Eventually it will be much cheaper and simpler to make really complicated things, like microprocessors and everything, in space and then send those highly complex manufactured objects back down to earth, so that we don't have the big factories and pollution generating industries that make those things now on Earth," Bezos says. "And Earth can be zoned residential."

The stunning Perito Moreno Glacier in Patagonia. We've sent robotic probes to every planet in this solar system. Earth is BY FAR the best one. We go to space to save the Earth. @BlueOrigin #NoPlanB #GradatimFerociter

It will be "multiple generations" and "hundreds of years" before this is a reality, Bezos said on CBS, but with Blue Origin he is working to develop the technology that will make it possible.

People will be able to live in space (in self-sufficient space structures) if they so choose, Bezos says.

"People are going to want to live on Earth, and they are going to want to live off Earth. There are going to be very nice places to live off earth as well. People will make that choice," Bezos says.

Astronaut John Glenn, the first American to orbit the Earth, wrote Bezos a letter in 2016 saying the work Bezos was doing would eventually make space travel as common as air travel.

"He wrote me the most beautiful letter just a few days before he passed away and I have it framed in my office and it is very meaningful to me," Bezos says. Glenn said in that letter he saw a future when we will board spacecraft like jetliners, and "when that happens, it will largely be because of your epic achievements."

"I think that is entirely believable," Bezos says. "If you went back in time a hundred years and told people today that you would be able to buy a ticket and fly across the world on a jetliner, they would have thought you were crazy. But that's the kind of change that can happen in just 100 years or less."

TWEET: Blue Origin is building the infrastructure needed to unleash the next generation of dreamers. I met these young people today, and the future is in great hands. #BlueMoon @clubforfuture

The first step in that journey is space tourism, Bezos says. Blue Origin is already testing its vehicle, the New Shepard, for taking humans into space for short tourism trips.

"Everybody who goes to space says they come back a little changed and they realize how beautiful this planet is and how small and fragile it is," Bezos says. "Something that we can't see when we are down here, but from up there it becomes obvious."

See also:

3 of billionaire Jeff Bezos' secrets to success

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Jeff Bezos' single teen mom brought him to night school with her when he was a baby