Camden Passage, London
A place where many discoveries go.
While members of the public always seem to make discoveries, about 4% of archaeologists "stumble upon" such things (worked out from Google searches for the phrases: "archaeologists discover" and "archaeologists stumble". Unfortunately, no one has constructed an N-gram to find out if incidents of awkward walking among archaeologists is on the rise or in decline. From the news reports, however, it is mostly only physical discoveries that are made by archaeologists and not intellectual discoveries. So perhaps they have as much trouble thinking as they they do walking (one imagines that thinking and walking at the same time would be especially difficult for them). Actually, archaeologists make all sorts of intellectual discoveries, but because of cultural lag, such discoveries can take many decades to be accepted as fact. By then, it is not usually "newsworthy" anyway.
Some archaeologists claim that people collect for enjoyment and profit. While this might be true, the statement is always disingenuous because it gives the impression that the motives of archaeologists are different from that. I once asked a very independent-minded history professor why we do what we do. He replied: "To exercise the mind, and to delight the senses". It strikes me that these motives, besides being honestly stated, are very survival-oriented and have been that way since we were all hunter-gatherers. Later on, people started to specialize more and live in cities thus becoming "civilized". The only problem being that the city dwellers were generally less healthy and less adaptive. Many civilizations have fallen because the people could not adapt to changing conditions.
I suppose that some archaeologists seriously believe that their motives are for the public good and that people can learn from history in sociologically valuable applications. I suspect, too, that these are the same archaeologists who have difficulties walking and thinking at the same time. When civilizations fall, it always seems to be a surprise to everyone at the time.
So what, then, is the sociological purpose of archaeology? If we measure this by the amount of energy used then the purpose is political. It serves nationalistic interests and cultures are recognized far less than nations. Far less energy is devoted to the use of archaeological sites as sources of income for tourism, and that is often somewhat illusory: while the management of the site might profit, the local infrastructure often has to spend more to support the traffic. A good study on the political use of archaeology is Archaeology Under Dictatorship and the editors explain that the use of archaeology by dictatorships is just an extreme end of other nationalistic interests served by archaeology. We also have to remember that archaeologists often excavate outside of their own nation and that permits to do so would be less commonly given to archaeologists who would go against the interests of these nations.
The best archaeologists (and historians) would agree with my history professor friend about their motives being for enjoyment and profit. It is almost axiomatic that the best work in any endeavor is accomplished by those who have a passion for it. It is pure pleasure, and pleasure is nature's reward for survival-oriented activities. The profit comes from recognition (although often slow arriving) and the ability to benefit from such recognition whether through book sales, paid lectures, academic advancement, or the realization of a life well spent.
Have an enjoyable and profitable weekend (however you define such qualities).