Archaeology, like cattle ranching or gold mining, produces multiple products that yield multiple revenue streams. The cattle grower produces meat, hides and perhaps breeding stock. In addition, some ranches produce cowboy-like experiences for tourists, adding another revenue stream to support the ranch. Similarly, gold mines produce other products, such as silver, in addition to the gold the miners are primarily seeking. It is the sum of all the revenues that can support the continuation and expansion of an operation, whether it be cattle ranches, gold mines or archaeological research.
More products mean more value produced and the opportunity to gain more revenues.
Thus the dig that yields no artifacts may still yield revenues from other sources. Just the prospect of finding valuable treasures would ensure interest in a site. A cooperative, productive relationship between collectors and archaeologists, even at sites unlikely to produce valuable display pieces, would have value simply for the prestige that such philanthropic activity would bring to collectors and their collections. Moreover, a site known to contain no artifacts holds little interest for looters anyway. The vast collections of treasures currently stored by museums, government agencies and others would also increase in value.