I agree with your sentiment but I have doubts about your actual analysis:
>Owning a house or an apartment might seem unnecessary in our modern society, until the next rent increase or some disturbance in your financial situation (assuming you're not sitting on a huge mortgage).
There's a large number of people (myself included) who are affluent but not affluent enough to own property without sacrificing standard of living. In a "steady state", you would expect the cost of renting and owning to be comparable, but in a bubble context owning is incredibly more expensive for the same unit because future rent increases are already priced in to the asset. That is the case for all of the top cities in the country.
Indeed, from my understanding many young people want to own property but have doubts they will ever be able to
> And why does nobody talk about how we have to pay every fucking minute, regardless what we do, in the share economy?
This is just an economic fact of life for everybody under capitalism, no matter how you slice it. If you invest capital to own something instead of renting it, you're constantly paying on the opportunity costs of another investments' dividends. This is in addition to the cost of maintenance and real estate taxes (for property), or the cost of maintenance, depreciation of asset, and cost of insurance (for cars), etc
> Who cares about the gearbox of a rented car? Just have a look at the interior of your average subway train. When the street I live in gets to dirty, why not simply move away?
I agree but these are collective costs, not individual costs (unlike the other points you made). Capitalism rarely factors in collective costs unless it gets to a certain breaking point for congress to act, like rivers catching on fire.
> While I love to be able to rent things that I cannot or don't want to own, I have the impression that this "share everything" paradigm is actually just a toxic mixture of permanent monetarization and centralised control.
"permanent monetarization" - that's just capitalism 101. Labor exists in a state of permanent monetarization because they don't have capital. If you have capital, see my above comment for evaluating whether you buy or rent+invest with said capital.
I don't agree with "centralised" - the long-term rental market is decentralized but should fall into the same bucket. There's no real reason you couldn't have a decentralized uber or airbnb, except that these services rely on technology for convenience, and there's all manner of problems with decentralized internet technology that makes it unlikely to succeed (I'd bet 10 bucks theres been an ICO for an uber-on-the-blockchain startup already).