Imagine the cross-section of thoughts you would hear all the time. Most of it mundane - work, family, food, shopping, day to day life. Some stand out through the noise - strong emotions like love, lust, happiness, pain, hatred. Some beautiful, some terrifying, some outright vile. A true cross-section of humankind's deepest thoughts.
Now imagine the loudest ones start finding others like them, and start to aggregate and cluster - mentally, not physically. Feeding and amplifying each other and getting louder and bigger. And they start to look outward, and find the thoughts they hate, and feed on those. There are no physical restrictions, no limits on distance or speed, just thoughts bouncing around and searching and filtering each other.
And imagine that once groups hit a critical mass, they also start to gather physically. And it's no longer just thoughts, but physical actions, encouraged by the entire group.
Of course - the Internet is not telepathy, there are filters, and not everyone participates. But it's the closest we've come to it as a species so far. And this is who we are...