Oppression is violence [1]. The willful disregard of laws enacted by a democratically elected legislature (from Uber's disregard of Taxi Medallions, airbnb's disregard of occupancy laws, to 2008-era banking scandals) of the upper class (successful entrepreneurs) is oppression against the lower classes.

Usually, this is taken care of through the courts, wherein the judicial system punishes people for crimes -- again, an act of violence. However, in the absence of punishment or a judiciary aligned with the interests of oppressors, the oppressed are morally justified in enacting punishment and responding to violence in kind.

[1] Paulo Freire, Pedagogy of the Oppressed, 1967.