Why is loneliness so common? It turns out it's not due to a lack social skills.

The main cause of loneliness is feeling misunderstood, and brain scans revealed this happens because lonely people process the world in other ways than non-lonely ones. But it's not just different from people who are happy with their social interactions who all show similar brain activity patterns among them; it's different from other lonely people too. This is why they can't just connect with each other to solve their issues together.

More info: https://arstechnica.com/science/2023/07/lonely-people-see-the-world-differently-according-to-their-brains/