It's about hype and economics.
Tech companies can theoretically scale well and are valued on the expectation of growth while normal companies are manly valued based on what they currently do. An app can basically be copied for free to millions of users once it has been coded and servers don't cost that much. A traditional company, say a car company, that wants to increase profits has to build a new factory or something. The problems arise when a companies perception goes from startup/tech company to normal company.

Example: wework was a startup that rented office space long term and lets it customers rent short term from them. Once people realized, that it was a real estate company and not a tech company it's value plummeted, it couldn't raise more capital and went bankrupt.

Edit: spelling

So I should be clear, I dont think theres anything special about Tech companies that should let them be treated differently. But for whatever reason, it is a fact that places like We or Tesla or Theranos or fucking Groupon gets stupid valuations just because they're "tech" adjacent.

If the market ever catches on that theres no secret ingredient (and as Zitron's shown, there are pretty visible public numbers pointing at this), we're looking at a correction at the trillion dollar scale. Or maybe we never ask Google to put up or shut up, and just keep the fairy powder in our eyes forever.