Just because 1 street in 1 town saw an influx of coffee shops, it doesn't mean the phenomena can be applied on a global scale. Outside of speculation, real-world adoption is what drives crypto prices and ultimately their success. You basically just restated your assertion after giving a metaphor that doesn't apply to crypto.
First of all, crypto is not a "currency", it's an asset. A currency (at least in modern parlance) is a pure unit of account and may or may not coincide with a particular commodity, be it electronic or otherwise. Even if it does, it never does so for very long since the unit of account quickly decouples from the value of the associated asset due to it being used to price everything from cornflakes to lending credit, so there's no natural monopoly there as far as the asset is concerned. (Take Sterling Silver and Sterling Paper for example, paper "Pesos" and metal weights etc. Sterling as a unit of account became a monopoly within its juristiction but silver itself remained as just another asset despite far out-performing its paper namesake for value).
Secondly, the "street" analogy wasn't geographical, it was with asset markets. Bitcoin may be "global" geographically but it isn't "global" in terms of the spectrum of investible monetary assets. For that reason the street analogy is relevant because we see the same economic dynamics in play as with the "original" coffee shop - a steady increase in demand going hand in hand with a steady reduction in dominance.