By definition, driving up the price is never an externality. The actual externalities from AirBnB are the noise, danger and lack of community that these apartm

By definition, driving up the price is never an externality. The actual externalities from AirBnB are the noise, danger and lack of community that these apartments impose on their neighbors. Even these would not really be externalities if the entire building knew about and allowed AirBnB renting. But in practice, almost all buildings forbid it.