When you break it down, I think philosophy is mostly metacognition. Psychology is still just as much philosophical as it is scientific.

There aren’t really huge difference between the three thinkers. Kierkegaard kind of needed Christianity as a coping mechanism.

Nietzsche genuinely did kind of break himself with stress. I don’t necessarily buy that he “went crazy.” I really feel like you can’t fully separate his alienation from German culture and Germany’s drift into fascism.

Camus forwards romanticism as a coping mechanism. He better understood science because of the time period he came from.

He was skilled at incorporating his philosophy into political and artistic results. I’d argue Camus had slightly more similarities with Doestoevsky than Kierkegaard.

There has been increasing information that he might have been politically assassinated by the KGB: https://amp.theguardian.com/books/2019/dec/05/albert-camus-murdered-by-the-kgb-giovanni-catelli

A lot of political assassinations happened in the 1960s.