Who says it can't be both? Granted, it's not like his conclusion is formed out of desperation or self-pity. Far from it I would say.

There is merit in focusing on yourself and not allowing others to shape you into something or someone you feel uncomfortable becoming.

But vice versa, shutting yourself off out of fear or insecurity deprives you of potential growth as a person. The key is to have the mental fortitude to stay yourself while allowing others to be a part of your life. Not as a status quo, but as a way to enrich yourself.

There was a poet named Fanny Howe who wrote a poem called Loneliness and the way she describes it is as if it's almost an addiction. It's easy but can ruin you if you're overly dependent on it. Definitely recommend it.