I think you underestimate how much speculation, gambling and crime happens in the fiat ecosystem. The forex, just to name one thing, is $7.5T exchanged a day.
In comparison, it’s estimated that Americans spend about $10T per year. I don’t have the numbers worldwide but America is a big piece of the cake.
So, speculation is vastly higher than regular spending, even for “regular money”.
Do you really not understand that the forex market has several real use cases and serves an actual purpose. Unlike crypto, it doesn't primarily or solely exist to facility crime and speculation. If you somehow shut down the forex trade, the global economy would experience severe disruptions. If you shut down crypto, nobody in the real economy would even notice.
In comparison, it’s estimated that Americans spend about $10T per year. I don’t have the numbers worldwide but America is a big piece of the cake.
So, speculation is vastly higher than regular spending, even for “regular money”.