As I have explained here before, cryptocurrencies are like a religion, not becoming truer merely because you can manage to find more believers. The tech bubble was an innovation arbitrage finance bubble turned subprime (similar to the real estate bubble earlier).
They are the same in the sense that they are both highly inflated value systems based on make-believe; they are different in how such make-believe is achieved.
The tech bubble relies on a chain of greater-fools of private investors who manage to drive up make-believe valuations until the last of the greater-fools, the public, finds out valuations do not live up to value post IPO. Animate valuations with regards to an investable asset as collateral, yet artificially overvalued.
Cryptocurrencies rely on trust being evenly distributed by more public believers in the value of a currency, without an asset to base the value and trust of such currency on. Hence it is an asset-less belief system, with inanimate valuations lacking collateral to back up such socioeconomic value — a self-perpetuating and hollow pipe-dream.
Both manage to induce the hallucinations of humanity in the same way the World Wrestling Entertainment (WWE) does. With make-believe, but financially rewarding when you are inclined to steal the innocence of sufficient greater-fools.
