Why do you think people are so mentally ill?

Better detection, more acceptance. But also Tylenol.

Tylenol.

Maybe we’ll find out it was microplastics all along.

Late stage capitalism. Also, "people" here applies mostly to the working classes in Western countries, and to an extent, some in the Global South with more significant levels of urbanization. Alienation under late stage capitalism and the US-led neoliberal world order leads to ever increasing precarity and desperation amongst the working class all over the world, as we face crisis after crisis, which is now worse than ever (and nothing new, obviously). In the imperial core, or the Global North (Anglosphere, Western Europe, North America), the dynamic is largely different than it is in the Global South, because every single aspect of life in these countries has become almost completely commodified and controlled by capitalist monopolies or duopolies alongside the death of "localism", in simple terms, sucking the joy out of life through profit maximization more than ever before. As fewer and fewer people control more and more wealth, in addition to costs of living skyrocketing through inflation, austerity measures, economic warfare (only to be worsened as far as the US goes following the latest stupid tariffs), leading to even more price gouging, this means that people need to take up an increasing number of jobs, or simply begin working longer hours (in addition to pension and other social security vanishing), leading to prolonged burnout and severe mental health issues, which also negatively impacts social lives through atomizing social structures. There's no doubt that this results in these "mental illnesses", though I've kind of observed that this term is often used in a very bigoted and ableist fashion that lacks nuance.

In the Global South, on the other hand, these dynamics occur differently. Many of us here have only known colonialism, imperialist destabilization, and exploitation in our countries, meant to stifle our socioeconomic development for the benefit of the imperial core, the same countries now suffering this perceived "social decay" the question concerns. We aren't living through "decaying" labor aristocratic capitalism, unlike the imperial core which attained its "high standards of living" through imperialist superprofits and exploitation, meaning slight breadcrumbs could be distributed to the working class in these countries to placate them and prevent them from gaining class consciousness by offering them a nice, mortgaged house, jobs in the service sector, consumerism derived from overproduction, etc. — instead, we're living under neocolonialism. This has an adverse effect at the same time, with the primary dialectic here being that, despite us still living under capitalism and thus still being vulnerable to its internal contradictions, we still retain degrees of non-atomized social structures more "free" of alienation, as well of subsistence-based lifestyles based on cooperation — in my country, for example, the informal economy is pretty much omnipresent.

It's not a binary. It's proof that capitalism needs to go. Basically, to summarize the above: You either live in a "developed" society where you enjoy temporary privileges and economic prosperity attained through imperialist superprofits that ever so slightly trickle down to you — but capitalist decay and crisis is inevitable and will only worsen for the working class which has no material interest in this mode of production (Global North / imperial core)

..or you live in poverty, IMF-imposed SAP austerity measures meaning zero social services (privatised and sold to imperialist financial cartels), and the economic dependence of your country on imperial powers (France, US, broader West) caused by the same force that leads to the temporary material privileges of the working classes in the Global North, yet your social structures aren't atomized (meaning no or less significant emergence of hyper-individualism in society, as seen in the West), because you're literally forced to cooperate socially as opposed to engaging in competition or wage slavery in the typical sense (the norm under capitalism) not to build a better world but to merely subsist (Global South / imperial periphery).

In both scenarios, though, there are no people in power looking after you - and most importantly, your class is not in power of the state.

Also, a relevant video video came to mind about this

People are not risen by villages so deficits are not smoothed out but strengthened.

Lacking social and emotional connection as a very individualistic society?? An increasingly worse quality education system and income inequality gap?? Insurance hurdles for those seeking mental health treatment?? Probably a lot of variables at play.

People who are well adjusted to a unjust world are also mentally ill.

It's hard to meet people who are honest and not trying to sell you something. In 20 years of studying psychiatry I see no cures and many serious side effects.