If I buy and then sell $100 worth of BTC a hundred times a day, have I created $100 worth of cryptocurrency trade or $10,000? Note I've only actually used $100 here (excluding transaction fees). If it's the second, then $33 billion dollars isn't really a useful number if many of these trades are just arbitrage by a few individuals utilizing the same dollars over and over.

I'd think a more useful statistic would be the amount of USD actually moved out of bitcoin exchanges rather than trades on the exchanges themselves.