On February 6, 2018, SpaceX successfully launched the Falcon Heavy, the fourth-highest capacity rocket ever built (after Saturn V, Energia and N1). The inaugural mission carried a Tesla Roadster belonging to Musk as a dummy payload.
In September 2018, Musk was sued by the U.S. Securities and Exchange Commission for a tweet claiming that funding had been secured for potentially taking Tesla private (at a price of $420 a share, an alleged reference to marijuana). The lawsuit claimed that verbal discussions Musk held with foreign investors in July 2018 did not confirm key deal terms and thus characterized the tweet as false, misleading, and damaging to investors, and sought to bar Musk from serving as CEO on publicly traded companies. Musk called the allegations unjustified and that he had never compromised his integrity. Two days later, Musk settled with the SEC, without admitting or denying the SEC's allegations. As a result, Musk and Tesla were fined $20 million each, and Musk was forced to step down temporarily as Tesla chairman while remaining Tesla's CEO.
As of January 29, 2016, Musk owned about 28.9 million Tesla shares, which equated to about 22% of the company. In January 2018, Musk was granted an option to buy up to 20.3 million shares if Tesla's market value were to rise to $650 billion. Majority shareholder approval for this package was approved in March 2018. The grant was also meant to end speculation about Musk's potential departure from Tesla to devote more time to his other business ventures. A report by advisory firm Glass Lewis & Co. to its clients argued against granting the options. As of December 31, 2019, Musk owns 38,658,670 shares or 20.8% of all Tesla shares.
By making AI available to everyone, OpenAI wants to "counteract large corporations who may gain too much power by owning super-intelligence systems devoted to profits, as well as governments which may use AI to gain power and even oppress their citizenry." Musk has stated he wants to counteract the concentration of power. In 2018 Musk left the OpenAI board to avoid possible future conflicts with his role as CEO of Tesla as Tesla increasingly became involved in AI through Tesla Autopilot.
In an interview with Joe Rogan in September 2018, Musk expressed his concerns about the dangers of developing artificial intelligence indiscriminately. In January 2019, Mark Harris of The Guardian noted that the Musk foundation had "added a line to its website, stating its support for the "development of safe artificial intelligence to benefit humanity".
As a merchandising and publicity stunt, Musk said TBC sold 2,000 "flamethrowers" in 2018, allegedly inspired by the Mel Brooks-directed film Spaceballs (1987).
In July 2018, Musk arranged for employees of his to build a small rescue pod to assist rescuers during the Tham Luang cave rescue. Musk, responding to requests for help from Twitter users, offered help and his The Boring Company contacted the Thai government. Richard Stanton, leader of the international rescue diving team, also urged Musk to continue construction of the mini-submarine as a back-up, in case flooding worsened.
Two days later, Musk issued an apology for his remarks. Then, on August 28, 2018, in response to criticism from a writer on Twitter, Musk tweeted "You don't think it's strange he hasn't sued me?" The following day, a letter from L. Lin Wood, the rescuer's attorney, dated August 6, emerged, showing that he had been making preparations for a libel lawsuit.
On September 6, 2018, Musk appeared on The Joe Rogan Experience podcast and discussed various topics for over two hours. One of the highest profile and controversial aspects of the program was Musk's sampling a single puff from a cigar consisting, Rogan claimed, of tobacco laced with cannabis. To Rogan's inquiry on how often he smoked cannabis, Musk replied: "Almost never. I know a lot of people like weed and that's fine, but I don't find that is very good for productivity... not for me." The Washington Post observed that, "In the media's hands, it became a story about Musk's growing instability."
Politically, Musk has described himself as "half Democrat, half Republican" and "I'm somewhere in the middle, socially liberal and fiscally conservative." In 2018, he stated that he was "not a conservative. I'm registered independent [and] politically moderate." Prompted by the emergence of artificial intelligence, Musk has voiced support for a universal basic income; he additionally backs direct democracy and has stated he thinks the government on Mars will be a direct democracy. He has described himself as a "socialist", but "not the kind that shifts resources from most productive to least productive, pretending to do good, while actually causing harm"—arguing instead, "true socialism seeks greatest good for all." He supports targeting an inclusive tax rate of 40%, prefers consumption taxes to income taxes, and supports the estate tax, as the "probability of progeny being equally excellent at capital allocation is not high."
In October 2018, in an effort to help solve the Flint water crisis, Musk and the Musk Foundation donated over $480,000 to install new water fountains with filtration systems for access to clean water at all Flint, Michigan schools. As of 2019, approximately 30,000 children in all 12 area schools have free, safe drinking water from the water filtration systems. Musk has been a top donor for the ACLU. In October 2019, Musk donated US$1 million to '#TeamTrees' a tree planting initiative to plant 20 million trees led by the YouTube community and in collaboration with Arbor Day Foundation.
On May 7, 2018, Musk and Canadian musician Grimes revealed that they had begun dating. On January 8, 2020, Grimes announced that she was pregnant with their first child. Grimes gave birth to a son on May 4, 2020. According to Musk and Grimes, his name was "X Æ A-12" (pronounced /ˈɛks.æʃˌeɪ.twɛlv/ EKS-ash-AY-twelv); however, the name was deemed illegal under California law, because it contained characters that are not in the modern English alphabet, and was then changed to "X Æ A-Xii". This drew more confusion, as Æ is not a letter in the modern English alphabet. The child was eventually named "X AE A-XII", with "X" as a first name and "AE A-XII" as a middle name.
In Iron Man 2 (2010), Musk met Tony Stark (Robert Downey Jr.) in a restaurant, and had a brief line regarding an "idea for an electric jet." In 2018, it was reported that Musk helped Robert Downey Jr. get into character for his role in Iron Man in the Marvel Cinematic Universe.