With a net worth reaching a staggering $300 billion, Elon Musk is expected to throw lavish parties or purchase sprawling mansions on top of owning and using the coolest tech in the world or making hefty donations to politicians.

But even with his mounting fortune that could make him the first trillionaire in the world, Musk maintains a modest lifestyle, with the multi-billionaire simply renting a $50,000 prefab home in Texas.

Why, you may ask, is Musk not spending that much money given his opulent stature? Why is he accumulating so much wealth and yet keep his personal life relatively simple?

His motivation, as he himself tweeted, is to attain his ultimate goal: transcending humanity from their present existence and transform them into a multi-planet species, an Inverse report said.

And this is the reason why Musk is slamming a proposed billionaire tax in U.S. Congress that would force him to pay $50 billion in government dues once enacted. The $50 billion, he said, could instead be spent on SpaceX rockets and tech that would bring humans to Mars, according to a Business Insider report.

Elon Musk Mars Plan: Regular Mars Trips to Form Human Colony

Musk is set to use SpaceX's 120-meter Starship spacecraft on top of a rocket called Super Heavy to build an Interplanetary Transport System (ITS) for frequent Mars trips as part of its space tourism goal. The spacecraft would be capable of ferrying 100 passengers from the Earth to the Red Planet and back.

Read Also: Elon Musk Tweets Wild Video of SpaceX Starship Becoming a Lightning Rod--And It's Real!

He is looking at launching 1,000 or more ITS spacecraft, each with the 100-passenger capacity, for those Mars trips. Musk is conceiving an architecture that would bring around one million people to Mars over the next century, forming a populous colony, Space.com revealed.

What could be the ticket price for the trip? Musk estimates around $100,000-$200,000, which he said is more affordable than the projected $10 billion using conventional spaceflight systems. He also estimated that it would cost $10 trillion to build a city on Mars.

SpaceX hopes to launch its first orbital Starship test flight in the next month, before a targeted Moon landing with the first woman and person of color on the lunar surface under NASA's Artemis program by 2024.

SpaceX, Elon Musk Show 'Gateway to Mars'

Meanwhile, the company showed a 90-second video detailing its "Gateway to Mars," with views of the Starship being wheeled to launch pad, taking off, doing complex flips and landing safely on the ground.

Musk also tweeted an astounding image of the Starship and Super Heavy with a full moon behind them at the company's Starbase site near Boca Chica, Texas. He wrote "Starbase under construction" on the tweet.

Having all these in mind, as he continues to allot most of his fortune to realizing his visions of Mars colonization, Musk said in a World Artificial Intelligence Conference in Shanghai, China in 2019: "It seems like a wise investment for the future."

Related Article: Elon Musk's Space X Plan to Mars Generates Comparisons to Video Games 'The Outer Worlds' and 'Red Faction'