> I guess you have never been to any other city in the world if you think that the suburbs are full.

Granted, I've never been to Paris myself, and never in the outskirts of London, but the stories from the Paris banlieues or the 2011 London riots tell enough of a story how fucked life there really is.

> Guess what: you can run more trains, bigger trains, higher frequencies, and you can build new tracks and new tunnels.

I've been born and am still living in Munich. Do tell, where the fuck can you run bigger or more trains here? The stations can't be extended in length, the Stammstrecke is already at a frequency limit that really can't be increased because the people have to get on and off and trains need time to accelerate and decelerate [0], and construction of new tunnels is expensive (as the U5 extension to Pasing is showing) or fraught with massive costs and overruns (see 2. Stammstrecke).

> Why do many companies prefer to move to big cities? Why do many people prefer to live in big cities?

Herd mentality and that there will be more people where they can source staff from.

The thing is, "rural flight" and the corresponding explosion in urban housing prices is a self-accelerating death spiral that cannot be stopped unless political effort is being taken: the less people work in rural areas, the more infrastructure has to close/consolidate to the point it becomes very unattractive, so less children will be there, and so employers will be leaving for urban areas, and so more people will flee, start from begin.

In urban areas, this leads to a lot of issues:

- dense buildings (i.e. skyscrapers) require huge amounts of resources and CO2 emissions to build - they must be made of really solid concrete simply to be able to stand, you can't use wood or other materials for fire safety reasons, fire safety becomes extremely complex and in the event they do burn (like in Grenfell Tower) you're looking at an immense death toll.

- there will have to be an enormous, multi-billion euros/dollars investment into public transit so that it's able to keep up with commuting - and the denser you build housing and employment facilities (offices and production), the denser and more expensive just that basic infrastructure will be. I haven't even included car traffic into planning because that's frankly impossible (and policies like in Singapore and other highly congested areas begin to reflect that reality).

- cities need "green space" like parks, large un-built areas or the Kleingärten you mentioned earlier: people need them for mental health reasons, the city itself needs it to not overheat [1], to draw in fresh air [2], and for stormwater retention [3]. Suuure, you can say fuck all of that, but you'll end up with depressive hellscapes and death tolls as a result. There's a reason why places like South Korea have pretty high suicide rates among developed, wealthy nations [4] - and housing is one of the biggest contributors [5].

- on top of the question of "how to get the people from home to work and back" comes the question "how to provide for these people": anything from water/sewage over electricity and internet to postal/parcel delivery will have to be at insane sizes; for grids this necessitates higher voltages/thicker pipes with corresponding increase in danger from leaks or backhoes

- no matter what you do, housing construction will never be able to catch up with demand, which leads to gentrification as low-income workers are "priced out" and have to endure a massively lower quality of life (long commute times, significantly higher proportion of rent to income, living in housing together with solely other poor people)

- actually owning real estate will become (or, let's be real, is) far out of reach for most people, which means they have to pay rent their entire lives, will never be able to build up wealth, and most importantly never be able to pass wealth down to their children

- both renters and buyers will be complaining about the high prices, with populists blaming immigrants or hillbillies for this issue

On the rural side, the feeling of being "left behind" and the resulting dereliction of everything necessary for life (infrastructure, schools, shopping, healthcare, ...) leads to frustration, that not rarely manifests itself into anti-urban and in the end anti-democratic attitudes.

Particularly the last four points are the ones with the most explosive political/unrest potential... hell just look at the US "flyover states", look at the elections in Hessen and Bavaria. It's no surprise that the far-right has gotten so strong over the last years, as the consequences of rural flight became undeniable.

Rural flight has to be stopped at all cost.

[0] https://www.abendzeitung-muenchen.de/muenchen/muenchen-u-bah...

[1] https://www.transforming-cities.de/baeume-verbessern-stadtkl...

[2] https://www.sueddeutsche.de/muenchen/giesing-neuperlach-lebe...

[3] https://www.ardalpha.de/wissen/umwelt/klima/schwammstadt-kli...

[4] https://en.wikipedia.org/wiki/List_of_countries_by_suicide_r...

[5] https://foreignpolicy.com/2021/11/05/south-korea-suicide-rat...