I mean this is a bit of a pointless argument in semantics, but if Michael was referring to the total supply, circulating or not, you can see the total supply produced by mining for both Bitcoin and Monero. It’s essential that the total supply is available otherwise the value is meaningless.

As for the total currency in circulation, it’s impossible to tell for any currency. People with cryptocurrency have died and the private keys lost, same as how cash can be misplaced.