The world's richest man chooses to live like a pauper, his ex-girlfriend has revealed in a baffling turn of events. 

South African and US tech entrepreneur Elon Musk had a vast wealth of $451 billion (US$306.4b) at his peak in November last year, making him the first person in the history of the world to cross over the US$300b mark. 

The Tesla and SpaceX founder, 50, is currently still top of the charts, with a net worth of $321b (US$218b) at the time of writing as per the Forbes Billionaire Index. 

Despite that, he "lives at times below the poverty line". 

That's according to his on-and-off girlfriend Grimes, who made the bombshell claim in a bizarre interview with Vanity Fair last week. 

Elon Musk's ex-girlfriend Grimes made the bizarre claim last week. Photo / Getty Images 

In a sit-down with the publication, 34-year-old Grimes candidly revealed that she did not live a life of luxury with Musk at times (as well as accidentally revealing she and Musk had had a secret daughter in December). 

"Like, bro wouldn't even get a new mattress," she told the reporter. 

While staying at Musk's Los Angeles pad, she discovered her side of the bed had a hole in it. 

However, Musk was reluctant to replace the essential item of furniture and suggested they ferry over the mattress from her place. 

"Bro does not live like a billionaire. Bro lives at times below the poverty line," Grimes said. 

"To the point where I was like, can we not live in a very insecure $40,000 house? Where the neighbours, like, film us, and there's no security, and I'm eating peanut butter for eight days in a row?" 

"I'm not super into amenities," she said. "But, um, I need nutrition and stuff." 

The news doesn't completely come out of the blue. 

In July last year, Musk casually mentioned in a reply to a tweet that he lived in a tiny shack worth $73,000 (US$50,000) at most. 

The billionaire was for a time living in a humble home that he reportedly rents from SpaceX on its launch site in Boca Chica, Texas. 

Elon Musk is reportedly a cheapskate and doesn't look after himself properly despite not having any shortage of cash. Photo / Getty Images 

The house, which was constructed from a box in just one day, measures a modest 35sq m and includes the bare essentials such as a living area, bathroom, bed and kitchen. 

Musk's tiny house is believed to have been produced by Boxabl. 

The Las Vegas-based company's houses are designed for affordability and ease of construction and look like studio apartments, although they are also customisable. 

That humble rental was the most googled celebrity home of 2021, with over 1.3 million searches globally. 

The size of Elon Musk's rumoured house. Photo / Boxabl 

The SpaceX CEO has sold most of his $147m (US$100m) real estate portfolio after making a pledge in May 2020 to get rid of all of his physical possessions and "own no house". 

In November last year, he sold his final nine-bedroom mansion for $44m (US$30m).