The economy will always correct itself, but historic drops and collapses have come and gone.

You are only loaning your own equity to yourself while paying high interest, which will lead your real estate business to collapse in the future.  

Every up cycle for decades in California some newbie has to get his equity out of town before the imminent collapse of California.

I soon realized I was a dummy and the acquisition was a B&H mistake since rental rates had fallen about $300/month (or more) in the neighborhood due to the tech collapse of 2001.

Not really a sinkhole where the ground collapsed but did have settlement that caused some small cracks in the walls and did require that repairs be made and they do classify this as a sinkhole. 

You'd be right if you were investing because of market euphoria and you're trying to get in and out and make your money before the market collapses.

Such factors left central banks with no option other than intervening, he said, speaking in his capacity as chairman of the global Financial Stability Board.https://www.theatlantic.com/magazine/archive/2020/07/coronavirus-banks-collapse/612247/https://www.greenwichtime.com/business/article/A-new-credit-bubble-gets-ready-to-burst-13911193.phpWhat comes next, dollar becomes so devalued that it triggers the great reset and crypto based economy. https://www.weforum.org/agenda/2020/06/now-is-the-time-for-a-great-reset/https://www.zerohedge.com/news/2018-11-22/did-imf-reveal-cryptocurrency-new-world-order-end-gamehttps://www.imf.org/external/pubs/ft/fandd/2018/06/pdf/fd0618.pdfhttps://www.zerohedge.com/crypto/bank-england-governor-signals-central-bank-digital-currency-coming

Gold bullion coin in own storage will be good enough during any major inflationary scare until they start mining the asteroids for it.But for your societal collapse escape hatch, you should keep a hermetically sealed stock of maybe 50 Kalashnikovs and 100,000 rounds of 7.62 x 39mm ammunition for them right in next to the gold.

What really sold me that #2 knew his stuff was when he pointed out that if I looked down the side of the building the parapet was actually curving in as the mortar collapsed.  

It also potentially (depending on the work) require some additional long term maintenance (e.g. sump pump replacement, collapsed interior weeping system).If at all possible any water penetration should be addressed at the source on the outside by digging down to the foundation, sealing all cracks, putting in a waterproof barrier, dimple board, stone, etc.