The activists that worked on behalf of labor were socialists (like, ACTUAL socialists, as opposed to the Democratic Socialists we have today), and often used violence to achieve their goals.
The activists that secured food safety standards engaged in vicious press tactics, some violence, and were often socialists.
The activists that fought segregation shut businesses down, broke laws, and some engaged in violence. A good many of them are still alive and fighting.
The activists that fight for LGBT equality are still fighting, because there are areas of the country that still have prejudicial laws.
The activists that helped create the endangered species list are still fighting, because the current administration and Congress are trying to gut it at this moment.
The same can be said for environmental activists who tackle pollution (see: Flint now has clean-ish water).
The term activist can mean a wide variety of things, but the ones I'm talking about do still exist. They are working hard, against a wide variety of problems, and sometimes that work involves marching. Sometimes it involves peaceful protest. Sometimes it involves scathing journalism. And though I do not approve of it or think it is the right way to do things, sometimes it involves violence. Categorizing all activists as racist thugs demanding someone else's stuff is a rash oversimplification of activism, attributing the actions and ideas of an incredibly small number of radicals to an incredibly large number of people.
I imagine you would bristle at someone calling you a racist, homophobic, undereducated, sweaty neckbeard, simply because you use this site. There are those around here that do fit that description, but they aren't representative of everyone.