Musk had previously shot past former Amazon CEO Jeff Bezos to take the world's wealthiest man title, but has now slumped back into second place after the Tesla shares dropped by 8.6 percent on Monday.
The share price hit - the biggest single day drop-off since September - could have been partially caused by tweets sent out by Musk in which he claimed that the price of Bitcoin and other cryptocurrencies 'seem high' .
Ahead of Tuesday's trading, Tesla shares were down a further six percent.
The comments that Musk made - an example of how Musk's recent tweets have affected real world financial matters - came after his car company bought up $1.5bn (£1.06bn) in Bitcoin, which had closed at $58,000 (£41,000) on Tuesday, yet another fresh high for the world's most popular cryptocurrency.
Speaking on Twitter to Peter Schiff, a gold investor and stockbroker, Musk said: "Money is just data that allows us to avoid the inconvenience of barter.
"That data, like all data, is subject to latency and error. The system will evolve to that which minimises both. That said, Bitcoin and [another cryptocurrency] Ethereum do seem high."
Just last week Musk had said that the Tesla decision to buy up that large sum of Bitcoin was not something that he took charge on personally.
Again, speaking on Twitter, he said: "Tesla's action is not directly reflective of my opinion."
He continued: "Having some Bitcoin, which is simply a less dumb form of liquidity than cash, is adventurous enough for an S&P 500 company.
"When fiat [government-issued] currency has negative real interest, only a fool wouldn't look elsewhere. Bitcoin is almost as bs [bullshit] as fiat money. The key word is 'almost'."
In disclosing its Bitcoin purchase to the US Securities and Exchange Commission last month, Tesla said it had 'updated our investment policy to provide us with more flexibility to further diversify and maximise returns' in order to allow for the investment of cash reserves in 'alternative reserve assets including digital assets'.
The decision, said the company, was approved by their audit committee and that since then Tesla had 'invested an aggregate $1.5bn in bitcoin under this policy and may acquire and hold digital assets from time to time or long term.'
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