Billionaire Elon Musk attracted criticism and controversy on Monday (July 16) after he called British caver Vernon Unsworth, who helped rescue the Thai footballers trapped in Tham Luang cave, a "pedo guy".

Mr Musk lashed out on Twitter after Unsworth told CNN in an interview that Mr Musk's prototype submarine had "no chance of working", doubling down on his unsubstantiated claim that Unsworth was a pedophile when questioned.

Here are five of the tech mogul's other choice antics that have met with controversy.

1. Derides Tesla unionisation drive, promises free yogurt and roller coasters

In February 2017, Buzzfeed obtained a copy of an internal e-mail from Mr Musk to Tesla employees urging them not to join the United Auto Workers (UAW) union which aimed to protect worker rights.

Mr Musk claimed that the UAW's "true allegiance is to the giant car companies" and that their tactics were "disingenuous or outright false".

He promised improvements to the workplace, including "a really amazing party", "free frozen yogurt stands scattered around the factory", and "a Tesla electric pod car roller coaster (with an optional loop the loop route, of course!) that will allow fast and fun travel throughout our Fremont campus".

2. Says AI poses more risk than North Korea, is most likely cause of WWIII

Mr Musk has been vocal about his apprehension towards artificial intelligence (AI). In August 2017, he tweeted: "If you're not concerned about AI safety, you should be. Vastly more risk than North Korea."

A month later, he nonchalantly offered his take on the possibility of World War III: "China, Russia, soon all countries w strong computer science. Competition for AI superiority at national level most likely cause of WW3 imo."

His remarks have been criticised by Wired digital editor James Temperton for oversimplifying complex issues and reducing them to pithy soundbites.

Mr Musk has clashed with Facebook CEO Mark Zuckerburg over the issue of AI, tweeting that Mr Zuckerberg's "understanding of the subject is limited" in July 2017.

Mr Zuckerberg, whose company uses AI for targeted advertising, among other functions, has called Mr Musk's comments "really negative" and "pretty irresponsible".

3. Labels public transport expert a 'sanctimonious idiot'

In December 2017, Wired reported that Mr Musk had called public transportation a "pain in the *ss" with "a bunch of random strangers, one of who [sic] might be a serial killer".

Public transit consultant Jarrett Walker then tweeted: "In cities, @elonmusk's hatred of sharing space with strangers is a luxury (or pathology) that only the rich can afford. Letting him design cities is the essence of elite projection."

The tweet was accompanied by a blog post Mr Walker had written about the "dangers of elite projection".

In a series of tweets, Mr Musk called Mr Walker an "idiot" before offering a sarcastic apology: "Sorry... Meant to say 'sanctimonious idiot'".

4. Sells 'world's safest' flamethrowers for protection against 'zombie apocalypse'

In an announcement worthy of an April Fool's joke, Mr Musk said in January 2018 that his Boring Company would sell the "world's safest" flamethrowers that would be effective "against hordes of the undead".

By Feb 1, all 20,000 units had been sold, raising US$10 million (S$13.6 million) for the Boring Company.

The state of California attempted to pass a bill, supported by police and firefighters, to restrict civilian ownership of flamethrowers, but failed to do so in the face of resistance from gun-rights lobbyists.

The product, billed tongue-in-cheek as "The Boring Company Not-a-Flamethrower", came with a set of hilarious terms and conditions, including the user's agreement to be responsible for "harming others", "burning things to the ground" and "showing off to my friends or romatic interests".

Not everyone was amused. Los Angeles politician Miguel Santiago, who authored the failed bill to restrict flamethrowers, wrote in a statement: "This product, in the wake of California's deadliest wildfire year in state history, is incredibly insensitive, dangerous, and most definitely not funny."

5. Calls out 'holier-than-thou hypocrisy' of media over negative coverage of Tesla

In May 2018, Mr Musk blasted big media companies "who lay claim to the truth, but publish only enough to sugarcoat the lie" after reports of Tesla's production issues.

He also blamed media companies and their loss of credibility for the election of US President Donald Trump. Mr Musk's remarks have been compared to President Trump's obsession with "fake news".

Mr Musk went on to say that journalists "are under constant pressure" to attract advertising dollars from "fossil fuel companies" and car companies other than Tesla.

He proposed setting up Pravda, a site for the public to rate the truth of any article and track the credibility of journalists, editors and publications over time.

Pravda was criticised as an attempt to "crowdsource truth" and "put reality to a vote".

SOURCES: THE GUARDIAN, BUZZFEED, WIRED, MASHABLE, NEWSWEEK, THE HUFFINGTON POST, THE WASHINGTON POST, THE VERGE, BORINGCOMPANY.COM, TWITTER