In my experience, I've noted that most 'social activists' are college students---and their commitment to the People wanes once they graduate and have to get a Real Job.
Of the die-hards that remain, they're either professional students, low-wage drones, or societal dropouts (i.e. leeches). There are enough well-funded-with-daddy's-money types to keep the group fed and stoned.
Overwhelmingly, the professional protests and people who organize them are labor union droogs.