I remember seeing interviews with Nortel's CEO where he bragged that most internet backbone traffic was handled by Nortel hardware. Things didn't quite work out how he thought they were going to work out.
I think Nvidia is better positioned than Cisco or Nortel were during the dotcom crash, but does anyone actually think Nvidia's current performance is sustainable? It doesn't seem realistic to believe that.
There is no specific reason to assume that AI will be similar to the dotcom boom/bust. AI may just as easily be like the introduction of the steam engine at the start of the industrial revolution, just sped up.
[0] "Planning and construction of railroads in the United States progressed rapidly and haphazardly, without direction or supervision from the states that granted charters to construct them. Before 1840 most surveys were made for short passenger lines which proved to be financially unprofitable. Because steam-powered railroads had stiff competition from canal companies, many partially completed lines were abandoned."
-- https://www.loc.gov/collections/railroad-maps-1828-to-1900/a...
That was similar to what happened during the dotcom bubble.
The difference this time, is that most of the funding comes from companies with huge profit margins. As long as the leadership in Alphabet, Meta, Microsoft and Amazon (not to mention Elon) believes that AI is coming soon, there will be funding.
Obviously, most startups will fail. But even if 19 fail and 1 succeed, if you invest in all, you're likely to make money.