Because blacks didn't simply neglect to exercise their rights; they were intimidated and bullied from doing so. Big difference.
Are you saying gun owners are not intimidated and bullied into not carrying their guns ???
I seem to recall a viral video of a LEO in Canton, Ohio threatening to execute a guy for CCW*..... I'm sure a quick search will turn up many other instances of people MTOB and being threatened with arrest, confiscation of their guns, etc, simply because they choose to excercise theri rights. Hell, we have people right here on this very thread that characterize those engaging in perfectly legal conduct as "asking for trouble".... I have no doubt that TPTB at the time characterized those in the Civil Rights movement of the 1950's-60's as "asking for trouble", or "rabblerousers"....
The Civil Rights Movement of the '50s was the culmination of 100+ years of abolitionist and civil rights activity. It had broad and deep support. The goals of the Civil Rights Movement were promoted regularly in sermons in churches and synagogues all across the nation. The Civil Rights Movement had charismatic leaders like Martin Luther King who could inspire the country.
I would submit to you that the Progressive Movement of today is the culmination of 100+ years of activity as well, and has steadily resulted in more government power and less individual freedom ..... the "resurgence" of 2A Rights is merely a backlash to that, and is not nearly as powerful as the movement it opposes.
*and were it not for video evidence and a personthat stood up for his rights, he'd still be out there doing it.