I disagree with your logic - people go out and buy expensive things with traceable money. Virtually no one in this day and age uses cash and if they do hold cash, it is unlikely that it's much. When someone uses a bitcoin ATM, it's confirmed that the person has bitcoin, and that the wallet they're using might have more value than the cash being withdrawn. Not sure why you aren't able to comprehend that point, especially given that a google search can prove that this logic has clearly been applied from multiple events in history.