The glass-in-the-ground people went spectacularly broke. I also suggest you look up the stock price chart for JDSU. On the software side, Ariba and Commerce One.
Yeah, hardware companies got hit hard. But dotcom also coincided with the de-industrialization era, with manufacturing moving out of the US, with a double whammy of commodization. So it's hard to disentangle the causes.
And then I can't really remember many Internet-focused software pick&shovels companies from that era. I was only starting my professional career at that time, though.
