In order for a person to enter the crypro market a person converts fiat/paper dollars, euros… etc. to ‘stable coin’ dollars.
The market cap of the total crypto market - the spot price quote multiplied by the amount of crypto currency may be several trillion in ‘stable coin’ dollars.
However the amount of fiat/paper dollar,euros,… collected by the crypto market is less than $100 billion in total.
In general the ordinary stock market is not connected to the crypto market. But a crash of the crypto market will affect all markets and economies.