Yes tech giant feeling insecure future existence includes Apple, Google, Facebook, Amazon, and Microsoft.
A few decades ago people could not imagine the world without AT&T. They controlled all the communication in the USA. Their technology was so valuable and their hold on the market so big, that they were eventually broken up into baby bells. AT&T never regained its pole position in technology.
The same thing happens to Google or Facebook. At some point regulations could come out to make the data a shared resource that all companies could use and increasing regulations about how such data is used.
Google or Facebook might not go completely out of business, but might not be in the same situation as they are today. The product Apple and Microsoft makes like iPhone or Azure, You can easily live without them. Hence these companies are less important to society.
It is also difficult for Apple to survive so far. However Microsoft is a tough nut to crack. It survived a concrete attack by almost everyone else in the tech business.
It survived the US government trying hard to break it. It survives the great firewall of China – something other US companies have not been able to do.
That said, Amazon might be the hardest to dislodge as their business involves building a large logistics chain that is going to be needed for a long time.