Construction costs are currently skyrocketing

They don't just complain less. They are now also laughing at everyone who called them crazy for spending so much money to save a little on heating costs.

That's exactly how it is. My brother-in-law (a building services engineer!) called us "crazy" over 2 years ago during the planning of our passive house. He said the extra expenses would NEVER pay off. He said this multiple times and "calculated" how little the last x cm of insulation would pay off. But then this year he himself built a KfW40+ multi-family house (my sister was more open to a high insulation standard and probably influenced him?) :D

as a tenant, you are not responsible for the maintenance of the apartment.

Not responsible (even if you have to pay for minor repairs and normally at least renew the interior paint/wallpaper). But you actually do pay for the maintenance of the apartment and the communal property. This is an obvious part of the rent. That is why the rent of a comparable property is usually higher than the interest costs of ownership (this is the "cold rent" of the owner).
The rent consists of: allocated capital costs, maintenance of the apartment and communal property, landlord’s profit

This does not apply to exceptional situations such as in Munich.

,

as a tenant, you are not responsible for the maintenance of the apartment. As a homeowner, as long as you own property and are financially and physically able, you spend huge amounts of money over the years because you want to "improve or beautify" your place. The garden is an example where you can financially strain yourself year after year. Eventually, the exterior needs to be painted, the kitchen is replaced because at the beginning you could only afford or wanted a cheap one. After 15 years, the rectifier of the photovoltaic system is at the end; a new one is needed, the bathroom also doesn't look so great after several years, the trend changes, and you've always wanted nicer outdoor lighting... So you do invest a lot of money over the years in a property if you don't want to live until the end in the decade before last.

You pay the costs for the "maintenance" of the apartment nicely through the rent. It just isn't as noticeable as with property ownership. Usually, you pay for the kitchen yourself both in a rental apartment and in your own home. Or do you believe the landlord will eventually gift you a new one? And if I have to renew my photovoltaic system at some point, I have already saved that money several times over through the operation of the system, unlike the tenant. In your own home, you do have the opportunity to adjust certain knobs to save money, which you do not have as a tenant. If we had stayed in our 90 sqm apartment, we would probably currently have 400€-500€ more in costs per month than now in our 140 sqm house. For our personal case, I do believe that building a house will be permanently cheaper for us than if we lived in rented accommodation all our lives.

Of course, in practice most homeowners do not have any _liquid_ assets in retirement that they can live off, because selling the house is out of the question

A stupid vicious circle, because a single-family home for two people, which for example was once built for four people, naturally ties up any available liquidity. Maintenance, renovation, refurbishment, and eating, traveling, driving, etc. are things you might still want in old age.
Thus, your own property quickly becomes a burden. And it also shows that, of course, in addition to your own property, you need at least one building block that secures liquidity.

as a tenant, you are not responsible for the maintenance of the apartment.

You are so cute. Do you really believe the landlord pays that out of his own pocket? You pay for it with your rent. Because he also builds up reserves. You pay off the place and for the maintenance. If he had to pay extra, he wouldn't rent it out.

because you want to "improve or beautify" your place.

The tenant pays for that too. Through allocated modernization and own contributions like painting, for example.

The garden is an example where you can financially stretch yourself every year again.

Gardening is a hobby and a way of life. Why else are there so many allotment gardens?

the kitchen is replaced because at the beginning one could or wanted to afford only a cheap one.

So does the landlord regularly pay for a new kitchen? I don't know that from my time as a tenant.

After 15 years, the rectifier of the photovoltaic system is at the end, a new one is needed,

Shouldn't that be covered by the profit from the photovoltaic system? Nice how some think you get something for free as a tenant. Only if you receive citizen’s income.

It remains questionable to me. I don’t know how old you are now. But you can relatively easily enter the invested equity plus maintenance costs into a compound interest calculator, so you get a rough overview of the capital then available.
I did this myself recently in another thread on the side and ended up with over 400k in assets. That is also correspondingly liquid. Of course, I left out many factors like inflation, possible adjustments, etc.
Therefore, I do NOT believe that you come out much better as a homeowner IF saving and investing are done consistently in comparison.
YES, an investment in well-being. But often nicely calculated in financial terms.

We did not contribute any equity at all