https://www.financecharts.com/compare/TSLA,TM/value/pe-ratio
So uh... Toyota's PE is almost 8, a bit down from its historical average of about 9 or 10.
Tesla's is currently about 115.
Down almost 50% from its highs around 200 during Jan 2025.
If Tesla's actual $$$ stock/share value dropped down to ... lets say a PE of 10... that would be... well ok it is currently still dropping rather rapidly, but lets say rightnnow its $225 per share.
If Tesla 'corrected' to a PE of 10, that's a share value of about $19.57.
About a 91% drop from where it is right now...
... which would wipe out around $700 billion of market cap.
These are ballpark figures based on a hypothetical scenario, this is not financial advice, but yeah, that is a way of looking at how overvalued Tesla is (or could be).
EDIT: Musk himself apparently owns about 410 million Tesla shares, as of Feb 2025.
https://www.investopedia.com/articles/insights/052616/top-4-tesla-shareholders-tsla.asp
So... a 91% reduction of 410m shares * $225 per share...
That would be a personal loss for Musk of about $82 billion, from this exact moment.
That'd put his net worth at about $273b, based on him having a net worth of $355b as of Feb 2025... but his net worth may already be significantly less than $355b, because Tesla has dropped a lot between the date of the source I've found for his net worth, and right now.
EDIT 2
https://www.forbes.com/profile/elon-musk/?list=rtb%2F&sh=7123ba5d7999
Uh wow yeah, ok, between Feb 28 2025 and Mar 18 2025, he's already lost about $34 billion... and is currently at $321 billion.
So... if you take $82 b out of $321, then he's down to around $240 ish.
Sadly... he would be the richest person in the world, even after that, he'd have to get below $210b ish to sink to #2 under Bezos, below about $200b to be #3, also under Zucky boy.