No, it did not. But I said nothing about the dot com bubble. I don't think that's the same kind of event as the examples of systemic failure that I cited. The dot com bubble did not cause the failure of large financial institutions.
No, the internet did not disappear when the bubble burst. The internet is not an asset that people are buying and selling. Subprime mortgages, on the other hand, actually are assets. For the borrower, of course, a mortgage is a liability. But for the lender, it is an asset, and those assets were overvalued on their books. Of course there is more to the story, but that was a major part of what caused the meltdown in 2008.
And no, mortgages did not disappear. But it suddenly became a lot harder to get a subprime mortgage, and the meltdown brought a lot of new regulation.
Something very similar happened with FTX. FTX and Alameda had assets on their books with extremely exaggerated values. When that information leaked, it caused on run on deposits.