What determines the success of a post on social media? Surely not its content. Success is determined by the prevailing discourse. A post implying some sort of elite knowledge seems foreign to the masses. They see something alien there, unfamiliar. A popular author is created by readers, created by discourse. Some authors achieve what they want surprisingly and effortlessly, publishing what resonates with the masses.
It happens, of course, that elitism becomes popular — not in its content, but in its form. It's popular to admire a painting by a famous abstractionist, for instance.
So then why write uninteresting posts? Well, writing lets the author dis-identify from himself and thus try on the role of a creator. That's the only purpose.