It is slightly more than adversity, as anyone can lose someone important or their job, suffer from brain trauma, etc. Upward mobility implies understanding and navigating through different sets of social rules and this can be extremely stressful and implies what sociologists call anomie.

The sociological explanation of this phenomenon is almost a hundred years old. You can read it here: Merton, Robert K. (October 1938). "Social Structure and Anomie". American Sociological Review. 3 (5): 672–682.

Sorry for the paywall, but you "hackers" know how to circumvent it, right?