That aspect of the herd instinct called groupthink is one of the strongest aspects in life. Groupthink rules the stock market. Every person has also experienced groupthink on the committee level. Mankind craves simple solutions to complicated problems.
The classic description of hubris leading to nemesis is "Quem vult perdere deus, prius dementat". Whom a God wishes to destroy, he first drives mad.
Disease is often underestimated - an invisible opponent. Dysentery killed far more Brits in Crimea than the Turks. Hypothermia killed more of Napoleon's soldiers than enemy action. So with the Companie des India settlers in Louisiana and de Lesseppes engineers in Panama.
Distance lends enchantment to the view.
The Latin American specialty is the predatory politician who has taken over the function previously performed by the anopheles mosquito.
How to kill a great city: Rent control. It induces low-skilled people to remain where there are few low-skilled jobs, which forces the highly-skilled people to live far away or perhaps leave. Then you bankrupt the landlords, often persons of modest means themselves, so that the buildings can't be maintained and often are lost. Mile upon mile of Harlem and the South Bronx have been burned out like German cities in World War II except that we have done it to ourselves. That, of course, shrinks the housing supply, raising the housing cost.
