That's a good point. I suppose I assumed that the 50-70% figure referred to front-side securities, futures, or commodity transactions (the equivalent of an end-customer buying a finished product in a retail transaction), rather than amongst various intermediate levels in a complex supply chain.
50-70% of auto transactions are between dealers who don't even drive their cars and only own them for weeks!
50-70% of bread transactions are between distributors and supermarkets who don't even eat bread and want to sell it in days or even hours!