Actually, they do. The classical economist's understanding is that money is created exogeneously, meaning a central bank prints it and it trinkles down into the mainstream by virtue of banks having excess reserves.

What happens in practice is that banks extend loans first and worry about their reserves later. By virtue of that, the enterpreneur gets a buck to invest in whatever he's doing, and part of that buck lands as extra pay (and thus economic activity) in the hands of workers who will spend every last bit of it for all intents and purposes.