The valuations remind me of the dot.com bubble in the late 1990's. One example from that era was a small company called WebVan, which was basically just a bunch of guys with Vans delivering food purchased on the "new Internet". It had a market cap of 10 billion, and one or 2 years later it went bankrupt.
If you look at a quality company like Intel, whose entire market cap could be purchased by a daily upside move in Nvidia after a good earnings day for Nvidia, you know something is wrong with Nvidia's valuation.
Valuation does matter, and it will always revert back to it's mean whether we're talking about the S&P 500 or individual companies.
The usual way it reverts back to it's mean is through a market crash. Storm clouds are on the horizon. I'm looking forward to buying Nvidia from the guy who took a -10x loss on it and is panic selling at the bottom of the crash.