I suspect some of the money that chased dotcom stocks in the 90's is chasing bitcoin and alt coins. There hasn't been a stock bubble since the 90's, so I guess bitcoin fills that need to speculate, that the stock market is not providing.
Crypto mining has been a portion but in no way “most of” the reason NVDA and AMD have risen. Machine learning, AI, and self driving are completely reliant on the products provided by the aforementioned.