Starting with “I don’t remember kids being that mean…” Watch “A Christmas Story” based on the author’s childhood memories, early post-war. Mean kids chase and bully the smaller ones, just because they can. That IIRC from growing up just after that era - was typical. Helicopter parents today spend a lot more time policing how their kids are treated than anyone did back then.
As for “Little Women” or similar stories - remember these sort of stories tend to concentrate on the protagonists’ social circle, so we don’t really get a glimpse of how minorities or outsiders are treated. Plus, in the “good old days” before cars, in small towns or big city neighbourhoods, everyone knew everyone else’s business and pettiness or meanness and public rudeness was much harder to get away with. We can thank the automobile and high rise apartments for the modern attitude which is very unique in the world - that you don’t know who your neighbours are, ten blocks from home nobody will know who you are, and you have no idea what your neighbours do for a living or about their family. Anonymous people can be meaner. I also saw something attributing this even more so to air conditioning - instead of getting out and sitting on the porch, everyone hides inside when it’s the least bit warm out. Plus - then internet cuts into people’s -especially kids’ - outdoor time.
As for overpopulation, as mentioned, the population in the developed areas of the world seems to be universally on track to be shrinking. Even China seems to be on track for a demographic bust, with two generations of “one child” fairly widely enforced. Modern society with middle class lifestyles requires both spouses to work. The cost of raising children has become a barely acceptable burden, and the welfare state takes care of old age care.
What I see as the most serious crisis of population is currently playing out on two or more fronts. In North America, the USA struggles ineffectively to close off its border to people looking for a better life from the south. In Europe, meanwhile, a more interesting dilemma. NATO cleverly took out Libya, one of the guardian states that held back the flood of migrants and refugees from further afield. As an unforeseen consequence, those people take advantage of the anarchy in Libya to attempt passage to Europe. (To a lesser extent, Australia faces a similar problem).
If most of the world’s remaining population growth is going to happen in poorer places like Central America, Africa and Southeast Asia that feed these migrations, then the problem will only get worse - especially if the destination countries fail to find a way to deal with this.
As for environmental depletions - it depends where. Despite the dwindling aquifers, the USA produces far more food than it needs. If food becomes more scarce, it just means less is used for cattle feed and Americans eat less meat, and less food is exported to feed other regions. SOme others are self-correcting. The destruction of the Atlantic cod fishery was what was needed to encourage REAL conservation; most states have reacted to dwindling fish stocks by expanding jurisdictions from 12-mile limits to the whole continental shelf. California is being forced to re-think water rights as well as conservation by the current drought, while drip-irrigation was known to Israelis decades ago.
So the richer countries will adjust by reductions in lifestyle and altering the consumption of resources. The places that WILL collapse are those that have no such room to give and no such control - so expect the crises and death toll to be worse in overcrowded undeveloped third world countries - as always. Interestingly, it’s economic and war refugees that are flooding the shores of Italy today - the starving hordes of Somalia, or the previous generations of Biafra or India, never migrated far; difficult to do on an empty stomach.