The dotcom bubble was fostered by tech giants like microsoft, apple and google. A very large percentage of newly made millionaires and billionaires in the world made their wealth in the tech industry. The Bill Gates, Steve Jobs, Steve Wozniaks of the world. There was something like a gold rush of eras past where a lot of people tried to hop on the bandwagon hoping they could get rich, too.
I think the dotcom bubble was very different from bitcoin. Profiteering and getting rich in 21 quick steps was the main motive fueling the dot com bubble. Bitcoin is different. Crypto currencies are something people actually use that have utility and real world functionality. Bitcoin is not a get rich quick scheme to most. From the beginning I remember there being a lot of people who believe in crypto and everything it stood for. That spirit and mentality appear to still be present today.
While the dotcom bubble may have been a mere stepping stone to many on their path to fame and riches, I don't think that type of mentality is as prevalent in crypto.