Rothbard:

An individual or a group of individuals acting jointly can…, at present, offer to pay money to the owners of land and labor, thus buying the services of their factors. The factors then work and produce the product, which, under the terms of their agreement, belongs to the new class of product-owners. These product-owners have purchased the services of the land and labor factors as the latter have been contributing to production; they [product-owners] then sell the final product to the consumers.

What has been the contribution of these product-owners, or “capitalists,” to the production process? It is this: the saving and restriction of consumption, instead of being done by the owners of land and labor, has been done by the capitalists. The capitalists originally saved, say, 95 ounces of gold which they could have then spent on consumers’ goods. They refrained from doing so, however, and, instead, advanced the money to the original owners of the factors. They paid the latter for their services while they were working, thus advancing them money before the product was actually produced and sold to the consumers.

Very good.

Another aspect of this that I didn't see mentioned is the work of identifying the opportunity. The worker may be the one making the product, but the worker may not even have known there was a demand for said product, or who the buyers are. Finding that stuff out takes time too.