There has been a tend for many years, of people choosing to book their holidays to coincide with all, or part of the festival, some who can afford to move out altogether, while some move out in order to rent their homes at exorbitant rates, to visitors.
It's certainly not a universally popular happening, but like so much of the arts, it's hyped up by those who make, or hope to make, a living from them. Usually with the help of a grant from the Arts Council.