95% of their problems are due to poor planning and shoddy construction. If they built it right from the start, it would still be great. But because of the nature of being underground, "simple" repairs stop being cheap or simple. So you gotta spend the cash upfront to do it right the first time.
This is a lesson in don't cheap out and kick the can down the road. Do it right the first time so you don't gotta redo it a second or third time, especially when redoing it involves digging up your entire house.
They bought it in 1994, before everything you ever needed to know about construction was on the internet. Short of having a preexisting familiarity with underground construction or having a buddy who designed missile silos their ability to identify potential future problems was likely quite limited.
True but I remember reading books, or collections of articles, on construction as a kid in the 70's and 80's with imprints like Mother Earth News and (iirc) Foxfire and more mainstream ones by Readers Digest, Time-Life, and Sunset. They covered things like this. It wasn't entirely out of reach if you went to a library.
This is a lesson in don't cheap out and kick the can down the road. Do it right the first time so you don't gotta redo it a second or third time, especially when redoing it involves digging up your entire house.