Street drinking is a form of anti-capitalism.
Capitalism is nihilistic, but its nihilism is self-serving. It ignores consequences (economic, ecological, social) but ultimately it serves those who wish to accumulate wealth.
Street drinking is nihilistic. But it is an inclusive form of nihilism, i.e. it includes the street drinker. It ignores consequences (economic, social, psychological, physical) for society as a whole, and for the individual who drinks.
It is anti-social and anti-individual.
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The street drinker inhabits space that is supposedly public, and constantly proves - to themselves and to those who care to watch - that public space is not public, and that it is monitored and policed, and that a hierarchy is maintained.
Street drinking is a ritual, towards obliteration. For the non-religious in society based on capitalist values, nihilistic rituals are the only meaningful ceremonies left.
To repeat the ritual, day after day. To be moved on from the same places, day after day. To perform these rituals is to (knowingly or unknowingly) perform a ritual against the incursion of the private upon the public. A performance of the chaotic towards the ordered.
Street drinking is a reminder that beneath the veneer of choice lies a chaos of determinism.