The line between solitude and loniness is time and choice.

In all their examples, those people choose to be alone for a period of time. But could easily choose not to. Also the time alone is limited.

Though, loniness can happen with other people, not having anyone at all is a very lonely feeling. I remember seeing videos of people saying they have no friends and start breaking down in tears.

As I age and past friendships fade away, without any new ones due to my personality, habits, I wonder how long until that'd be me.