I guess we will disagree on this point. The person who buys a crypto, any crypto, with dollars from a stimulus check exchanges those dollars with someone who would rather have dollars than a measure of crypto currency. Dollars are a poor form of savings, given that they slowly inflate and lose value over time. While it's possible that the crypto seller stuffs those dollars in a mattress, thus taking them out of circulation, this is highly unlikely. Far more likely that they spend them for goods and services, or reinvest them, in another crypto or an equity share or some other investment commodity, in which case the new holder spends them or reinvests them. At some point they almost certainly reenter commerce.