We’re all Heideggerians now; we’re all willing to see, in far-fetched and under-informed philological analysis, the excavation of our concepts’ hidden meanings. So: here’s my New Oxford Dictionary of English.
Affluent adjective 1 (especially of a group or area) having a great deal of money; wealthy: the affluent societies of the western world / (as plural noun the affluent) only the affluent could afford to travel abroad. 2 archaic (of water) flowing freely or in great quantity. Noun archaic a tributary stream. ORIGIN late Middle English (in sense 2): via Old French from Latin affluent- ‘flowing towards, flowing freely’, from the verb affluere, from ad- ‘to’ + fluere ‘to flow’.
Let us, then, see the affluent as a tributary stream, through which something (money, say) flows freely and in great quantity. Let’s notice that this imagines affluence (in accordance with economic theory) not as a state but as a process. To be affluent is not, principally, to possess money, but to act as a conduit for it. Money’s meaning is movement: affluence must be maintained through expenditure. If the stream stops flowing, it’s not a stream any more. Where does it flow? To firms, institutions, financial centres, the great sea of the banking industry. Evaporation; condensation; precipitation. If we’re lucky, after the downpour, we can stand close enough to the stream to slake our thirst. Only the affluent can save us.