It is common advice that “Think before you Speak”, as one’s own words can harm him more than anything else.

And it can’t be true in the case of Tesla’s Elon Musk whose one Twitter post cost him the status of being the world’s richest man overnight.

Elon Musk is no longer the world's richest person after Tesla Inc. shares slid 8.6% on Monday, wiping $15.2 billion from his net worth.

Tesla's biggest decline since September was fueled in part by Musk's comments over the weekend that the prices of Bitcoin and smaller rival Ether "do seem high."

His message -- via his favoured medium of Twitter -- came two weeks after Tesla announced it added $1.5 billion in Bitcoin to its balance sheet. The cryptocurrency, which has surged more than 400% over the past year, tumbled for a second day on Tuesday, at one point slipping below $50,000 on scepticism over the durability of its rally.

Musk also tweeted earlier Monday that the company's Model Y Standard Range SUV would still be available "off the menu," backing up reports from electric vehicle news site Electrek that the model had been removed from its online configurator.

Musk drops to second on the Bloomberg Billionaires Index of the world's 500 richest people with a net worth of $183.4 billion -- down from a peak of $210 billion in January.

Amazon.com Inc. founder Jeff Bezos reclaimed the top spot even as his fortune fell by $3.7 billion to $186.3 billion Monday.

The two billionaires have been swapping places since January as the value of Tesla fluctuated. The stock surged as much as 25% to start 2021 before wiping off almost all of this year's gain. Musk briefly overtook Bezos after his rocket company SpaceX raised $850 million earlier this month, valuing the company at $74 billion, a 60% jump from August.