Role of booty in the economy during the Prophet's time

During the Medinan decade of the Prophets' time, the Muslims led expeditions in order to obtain booty. It is widely held that these expeditions enriched the Muslims. However, the cost of the expeditions themselves, the cost of living at the time, and the losses undergone greatly surpass the booty obtained. The basis for the economy must therefore have been agriculture, trade, and industry.