Construction costs are currently skyrocketing

Photovoltaics, which could never be worthwhile at the current moon prices. And that stuff has a lifespan of... 15 years? Maybe 20.

Experts currently speak of 30 years. Photovoltaics have proven to be energetically profitable in under 5 years.

A concrete cistern lasts... 40, 50 years? The 3-4,000 EUR is very well invested money.

Calculate for me how much money I can save with that. My estimates for a 3000€ cistern are about 50€/year. Unfortunately, that means it only "pays off" well after the 40-50 years. With cisterns, unfortunately, it is often like with photovoltaic storage. Always full when you don’t need it and always empty when you urgently need it. It becomes more sensible if you use it for the toilet and garden, but then you will never get by with 3000€.

It costs an incredible amount of energy to turn wastewater into drinking water... for the lawn?

Yes, how much energy does it take (in kWh) to produce one m³ of water? I’ll gladly help you with some numbers: If it is "just" pumped from the ground, it’s about one kWh. If it has to be produced by reverse osmosis, then 4-9 kWh. A well-dimensioned photovoltaic system easily produces that on the days when you need water for watering.

I understand what you mean, but I consider this view a misconception. With property, you are 1000 times wealthier than these people and also significantly better off. You have assets and can do with them whatever you want. Not selling is also your own choice. Others do not have these assets, the freedoms associated with them, and many other freedoms. It only seems "better" at first.

Not everyone is equally wealthy.
What if, for example, you bought an apartment early, paid it off over 20 years, and then become unemployed/unable to work, etc., and are supposed to sell the apartment.
Having an apartment does not automatically make you "rich." I also wouldn’t immediately call anyone with a house "rich."
It depends on the location, condition, and your other financial circumstances.

IN THAT CASE, it should be done consistently. That means: there is no more social assistance and everyone is truly responsible for themselves and their lives, so the abolition of basic income, etc., no more rent payments, and you only receive medical treatment if you actually pay contributions yourself.

I find THAT fair (and then, if you want, you could also do it the way you suggested).

Not everyone is equally wealthy. What if you bought an apartment early on, paid it off over 20 years, and then you become unemployed/unfit for work etc. and have to sell the apartment. Having an apartment doesn’t automatically mean you’re "rich." I also wouldn’t immediately call someone with a house "rich." It depends on the location, the condition, and your other assets.

Not being "equally" wealthy doesn’t mean you aren’t wealthy at all. Whether a house is worth 200k or 450k—that’s all measurable, likewise how wealthy someone is can be measured. If you have paid off your apartment over 20 years, you have built up wealth. If you then become unemployed, you are entitled to unemployment benefits (ALG1) for quite a while, during which you don’t have to touch your savings and can look for a new job. Only afterwards do you fall into basic security, and it’s not called that without reason. Then assets are offset. That’s a safety net to survive, funded by society as a whole. Personally, I would be much more annoyed paying people’s bread with my earned contributions who still own a little house or a condominium than people who have fled here with only the clothes on their backs because of war and suffering.

THEN it should be done consistently. That means: There is no more social welfare and everyone is truly responsible for themselves and their own life, meaning abolishing Bürgergeld etc., no more rent payments, and you only get medical treatment if you actually pay contributions yourself. THAT I find fair (and then you could do it the way you suggested).

You can quickly look beyond your own borders to the USA to see how such a system works and what it means for the lower income classes. That is truly capitalism in its final stage. Of course, you are free to prefer that; personally, I prefer living in a welfare state.

If you have paid off your apartment for 20 years, you have built up wealth as a result. If you then become unemployed, you are entitled to ALG1 for quite some time, during which you don’t have to touch your savings and can look for a new job. Only afterwards do you fall into basic security, and it’s not called that for no reason. Then assets are taken into account.

That’s true! But I believe the time window is very small. I think it’s only 12 months during which your own assets are irrelevant for state support. But there is also the case where someone simply inherits a dump and has to sell it anyway because they can’t even afford 10% inheritance tax (let alone necessary renovations, heat pump, etc. etc).

You can quickly glance across the pond to the USA to see how such a system works and what it currently means for the lower income groups. That is really capitalism in its final stage. Of course, you are welcome to prefer that, but personally, I prefer living in a welfare state.

And what is the solution then?
It annoys me – to put it mildly – that I work and have to spend 40% of my net salary (which is a small four-figure amount) just for the warm rent. Others come here and get their rent paid + citizen’s allowance + medical benefits.
It triggers me so much and my brain just can’t comprehend that the majority of the population is totally fine with this and doesn’t question it.

All houses in my district that are offered for sale at around €300,000 on Immo are in need of renovation because they’re too old (from the ’60s, ’70s). So you can safely add another €100,000, usually even more. And then there are the costs for a heat pump (probably another €100,000 additional).

How can anyone believe that all this makes sense?

With real estate, one is, as a rule, not wealthy at all. On the contrary, the capital is tied up and in case of doubt, the bank won’t even give you a loan for new windows.
Do you sell the garage to go on vacation? Or the roof, for a new car?
Anyone who wants to build wealth that they can use should do everything, but not acquire [Immobilie].

Photovoltaic, which at the current moon prices

1100€/kw fully installed = moon price? Really?