>> Leverage is great when prices are increasing, but not when prices are moving in the opposite direction.

This.

I worked for a medium sized company in the early aughts. It was a family owned business. The eldest brother was the owner and we often had lunch and he would tell me that once I make x amount, then I should buy this kind of real estate. When you get to this xx amount, then buy this kind of real estate. Fuck the stock market, only real estate goes up in value every year like clockwork. At the time he had several rental properties and three or four houses located all over the country.

That was until 2008.

Its funny, I ran into him at an architecture conference a few years back and one of the first things he said to me was, "Remember that real estate advice I was giving you? You can completely ignore that now!" and we both had a good laugh about how drastically the market had changed since 08'.

Sounds like your friend did something wrong with his investments. I had rentals before 2008, and bought more during the crash in South Florida for pennies on the dollar. It was a great time to buy.