I've come to think it's about individualism vs collectivism, of sorts. If I assume the position of people being responsible for their well-being, including mental, that means what _I_ got is justified by my own virtue and the other factors are coincidental and have little influence. If instead I assume people can be severely affected by factors outside of their control, then my figurative riches are just an accident of being born in a well-off environment, with a good set of genes, into position of privilege, etc.
If you think about existence conditions as being more chance-based, then you can no longer assume that everybody has equal chances, and it raises questions of fairness and justice that might lead to a redistribution of wealth and dismantling of certain power hierarchies if you push it far enough. Instead our society chose to build a cult of mythical "self-made men" who deserve what they got, and if you got nothing, it only follows naturally that you've never deserved it.
A side effect of that is that your parents believe you (and maybe themselves) to be one of those deserving people who just temporarily got out of wack and need to put in a bit of work to get back on a track to success. Such perception of self helps to not fall into despair over the state of contemporary civilization, but also blinds one to the actual causal links leading to their existence conditions.
All I know now about chronic stress, depression and suicidal ideation is that it's super complicated and affected by so many factors it's hard to come up with a fully functional model, let alone cure people. We are far, far from making any ethical claims as to why e.g. depression and anxiety happen and what should be done to prevent them, if anything.
And this hole in knowledge, as it's often the case, people fill with pure bullshit.
