My daughter and son-in-law purchased a 1960’s era house in a very desirable neighborhood that we knew needed extensive renos. The sellers did no maintenance and tried to DIY fix problems, like when the 2-story deck completely separated from the house, they tried to reattach it with a thick caulk. They employed the same engineering to the stone fireplace, which also had completely separated from the wall (it may have never been attached). My favorite was when my husband and kids took down the walls and it rained bugs!
They ended up having to take it down to the concrete foundation and walls but luckily my husband does this for a living, so it didn’t phase him. They bought it for low $300’s and un-remodeled homes in their neighborhood are currently selling in the $600-700’s with remodeled homes selling for $900’s & up. I think when all was said & done, they put about $70k into the remodel but it was a gut job. It was a good Covid shut down project - they did most of the work themselves.