Are your neighbours your close friends? Most likely not. Most likely they're strangers from different walks of life who happened to be your neighbours purely by

Are your neighbours your close friends? Most likely not. Most likely they're strangers from different walks of life who happened to be your neighbours purely by accident. Since people are different, your neighbours will likely have different opinions than you. Same for people you meet in a bar. If it's not X-political-gang bar, you'll probably meet all kinds of strangers from the area and away. Meanwhile your closely knit friends' circle is mostly of people who think similarly to you. Or at least people who you're comfortable with. People in general are lazy and rarely look up different opinions for the sake of it. They hear whatever opinions they bump into. Be it their neighbourhood and bar or their FB feed. Another thing is, back in hood & bar times, people would not only hear different ideas, but see that it's regular humans behind them. That there's no inherent us vs them. In social media, it's easy to just write it off as bullshit, the other person as stupid and block them. "Well known people on each side" is a part of a problem. They're "them". It's harder to find common ground with some celebrity you don't agree with than with a neighbour you interact with daily and who is a great human being other than few political points you don't agree with. Of course humans were always prone to "us vs them" and echo chambers. But today's technology makes that very easy to find very specific echo chambers. A century ago language was the echo chamber limit. Thus people speaking same language in close enough geographical proximity would usually get along pretty well. Now that is more or less gone, but we have echo chambers in between people living relatively close to each other. What next, reorganising into virtual states defined by political opinions? Liberal and conservative living next to each other, but following different laws? This is how many countries were run up to modern times actually. Jews having different laws in some European countries. Christians having different laws in Ottoman empire. Neither of these ended well.