The common pattern tends to be that a focused, outlier minority, through consistent and concerted effort, can change the public perception on a topic until it becomes the publicly-advocated goal, and then a culture can shift.
The US 'Founding Fathers' were a relatively small group of merchants, land owners, an publishers that were, if you will, "thought leaders" of an American "englightenment" movement that saw significant opportunities if they could toss the foreign rule of Great Britain. But "Let's break loose from the monarchy" was hardly a common public opinion before a combination of a series of writings made by an absolute handful of individuals in the group and a series of publicized bad tactical / strategic calls made by the representatives of the British government in the Colonies.
(It may be difficult to tease apart cause and effect on this topic, however; consider the possibility that there are fringe thinkers pulling in all directions, but as circumstances change, an accident of incidents may bring some of the fringe thinkers to a position of being less fringe. People were saying police in the US were too brutal to minorities for decades before combination of ubiquitous smartphone cameras and multiple disconnected high-profile incidents that common folk considered brutality started to bring public perception around to that way of thinking. We're in the middle of a cultural fight right now, but if policing as it's done in the US does fundamentally change, history will probably record a story of Black Lives Matter leaders bringing about that change. And if it doesn't change, this era of US history will probably hold a place in history books similar to the one the LA riots hold).