Bought a house cheaply. What now?

You were not specifically meant, but if you feel addressed, you seem to be of the opinion that it applies to you.

“Your friend acted without any knowledge and without a well-founded plan”
“Wow, is that courage or is it called something else?”
“pure profit-seeking/greed”
“Your friend needs something different than a house construction forum”

Has absolutely nothing to do with the questioner's concern but are derogatory statements on your part.

You were not specifically meant

....yes, you quote me exclusively and criticize my statements, then at least stick to it, I can handle that.

you seem to be of the opinion that it applies to you.

Yes, I am.......this follows exclusively from what you wrote I gladly accept criticism, I can read at least somewhat-

Some acquaintances who have some knowledge have also looked at the house and said it was a good price. But yes, thanks, we will go through it again with a professional.

From this it can be concluded that the acquaintances with "some knowledge" apparently have even more knowledge of this subject than OP+Freud. Hence their positive agreement to the note that they want to go through it with a professional.

“pure profit-seeking/greed”

"Profit-seeking"....as the OP said. "Greed" I added because the various definitions strongly suggest it when someone without deeper knowledge of the circumstances (as described by OP) embarks on such an adventure (house purchase) out of profit-seeking (understandable and not forbidden), which she clearly cannot even remotely assess (hence also the OP’s thread only AFTER the purchase). Since the OP apparently seems to be involved in it in an unclear way (he/we...), I was honestly shocked that she might possibly/apparently become involved in something that she cannot assess and that can permanently and severely affect her life. Therefore I live with your repeated criticism and am aware that these were no flowers for the OP, nor should they have been. She will do what she wants anyway, but I myself was always glad when someone told me their opinion directly if I was maybe too euphoric. This was my intention here and as soon as the OP signals to me that she no longer wants to read this or needs a referee, I will of course respect that. For your understanding: I prefer direct address, therefore I also encourage you to address me directly if you have exclusively quoted me. You and of course the OP can also be sure that it is not my hobby to "(de)value" unknown people, not by any means. But if I believe I recognize something so dangerous in a (young) person then I say it, maybe even somewhat out of a sense of social duty. Therefore I also accept your criticism and your point of view seriously; you should not suspect ill intentions on my part.

That's what I call risk. Schabbooo

I am only responding here once because such disputes in forums are pointless.

"yes, you exclusively quote me and criticize my statements,"

I first quoted you when you addressed me directly and made it clear that you felt addressed. I have no reason to quote others because I do not want to address anyone in particular.

"Yes, I am.......this exclusively follows from what you wrote"

Only after I quoted you as written above was there a direct reference to you.

"From this it can be concluded that the acquaintances with 'a little knowledge' apparently have more knowledge about this topic than TE+Freud."

The text from Berenike with this passage was only posted after you had already posted, so you could not have concluded from Berenike's first post that there was little knowledge.

So, slowly now. There's no rush at all. The first thing that has to happen is an honest inventory. What was done when, what still needs to be done? What are properties in the town worth? Do you want to live there or not? Think for yourselves or he should think about how to proceed. If the house was bought with equity, you have more time. I am also just an amateur. But I have bought and renovated two old houses. A lot in EL. So, think about it. Take photos and upload them here. Photos of heating, water, sewage, roof, windows. Often there is a date stamped between the panes of the window with the manufacturing date. Was there a pub in it? Inquire at the municipality about the cost of a change of use. Draw floor plans and upload them.

I am only responding to this once because such disputes in forums are pointless.

Considering that this realization exists, quite a lot still comes up...

so you couldn’t conclude from Berenike’s first post that there was little knowledge.

If you had read post #1, you would know that the OP had not made the necessary considerations BEFORE the purchase and is now (AFTER the purchase) looking for "knowledge" here in the forum (see post #1). Ergo, at this point, there was at least insufficient "knowledge" available; fitting to that, the site inspection with acquaintances with "a bit of knowledge".

What other options would there be according to your experience? Where is the return best?

Since you describe my statement as unsympathetic or demeaning, I would indeed be interested in your – factual – opinion on this, which the OP might also want.
Other than criticism of my choice of words, nothing else has been read from you so far on this matter, although the OP specifically asked the forum members for this, including you (see post #1).
I have written my position directly without beating around the bush because I fear, based on what has been written so far, that the OP could possibly slip into something extremely unpleasant for her too credulously.
So , rest assured, I am not writing with ill intent but genuinely tried to point out with clear words the high risk of thoughtlessness.
Let’s leave it at that, and I do thank you for your criticism, which usually (especially for me too!) leads to the necessary reflection.