Well, this simulator runs on a simplified behaviour.
Citizen wealth seems based on services provided to them as well as their education.
A Citizen, who has just moved into the City can climb to the top ot the social ladder, provided he's good in school, so he can get one of the many well paying high educated jobs.
My theory is, that the world of Cities:Skylines is moving towards a post scarcity future, with generally honest citizens, who have excellent work ethic.
These people seem to emphasize the positive traits of humans.
I have tried to speculate on their system of government too. Maybe they are subjects of a fatherly king and serve their monarch with undying loyalty.
I mean, the Citizens seem so enthusiastic about life, like little puppies, or kittens.
I didn't get the mismanagement achievements, because you have to force them into misery. You want to get the crime achievement? Your upstanding citizens will respect the law, even without enforcers, until circumstances force them into crime.
Want to get the Lazaret Plaza? You'd have to pollute the city water, because your Citizens eat healthy food, excercise regularly and maintain their positive outlook on life. These people are not religious, they are religion itself, possessing the seven virtues.
Castitas: The citizens will not overpopulate my city. If there are not enough houses available. If there are no more houses available, they move out of your city to find education elsewhere. Their parents will limit reproduction to sustainable levels, if you don't build additional houses. (Sometimes, they drop below, and your city experiences a temporary dip in population.)
Temperantia: The citizens excercise incredible self control. They will abstain from unhealthy food, stay out of trouble, finish their education. Unless you expose them to hazardous materials, they will continue to be healhy, even during old age.
Industria: After they finish their education, your citizens will quickly find employment and enrich your city even further. Even freshly migrated citizens can reach a level 5 dwelling through hard work and their unwavering dedication. If a good job is available, they will to all the necessary preparations to fullfill that position.
Patientia: My citizes seem to play the long game. They don't get mad, if my little village doesn't offer all the amenities a metropolis has, instead they will build one with me. Even if they may not see the day, the city reaches 1.000.000 inhabitants, their happy little families will continue to strive for all the time it takes to get there.
Caritas: Your citizens don't seem greedy. In fact they even provide all the public funding you could ever desire, without objection. Your citizens will not evade taxation, as it would hurt them in the form of underfunded city services in the end.
Humanitas: Your citizens seem kind to other living beings and especially their fellow citizens. Plus, they don't engage in chirp wars.
Humilitas: The citizens don't mind working at a less prestigious position, as long as it's appropriate to their level of education. In fact, they seem to always occupy the positions in the garbage services, as they know, it's for the benefit of everyone if the garbage is collected.