I am much happier standing or sitting on the ground in public than sitting on a chair, bench, etc, because I feel more free to move around. If I'm standing and someone gets too close to me, I can surreptitiously move a little bit away, while it would be more obvious if someone sat next to me and I moved. Sitting on the ground, I feel like it's more acceptable to sit in my preferred position, with my knees pulled up to my chest, which makes me more comfortable. I guess I feel sort of trapped if I'm sitting in a chair or something.
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Yet in my new wildness and freedom I almost welcome the bitterness of alienage. For although nepenthe has calmed me, I know always that I am an outsider; a stranger in this century and among those who are still men.
-H. P. Lovecraft, "The Outsider"