As for your claim that rioting and the like can never be beneficial, that's plainly wrong.
Take for instance the Curaçao uprising in 1969 [1]. Workers protested wage discrimination and it turned into a mob that burned down 43 businesses and 10 other buildings, primarily those owned by white people. Guess what? The protest was a complete success, they got the wage they asked for and they got new democratic elections to boot.
I reiterate: people protest and riot because it works.
[1] https://en.m.wikipedia.org/wiki/1969_Cura%C3%A7ao_uprising