If one is close to being paid off, personally I'd ride that one out if you don't need the extra cash flow now....If it's going to go up significantly when it's paid off and you want to have it paid off.

Keep putting in the work and riding the rollercoaster of RE investing.

It has been a good ride up since that paper was written but now the city is a competitor as they tie the landlord's hands and then buy properties to build low cost housing on expensive land.

As long as you have positive cash flow, you can ride out any turbulence in the housing market and choose when to sell in the future.

AC units go out, hail storms cause roofs to be repaired, etc. 

It's like learning to ride a bike at first it is hard to get it going but after a while it gets really easy.

I also had to convince my wife to come along for the ride each time.

Mining is a niche within a volatile industry that has been a roller coaster ride over the past few years and also has some big variables that are uncontrollable: global regulation, hardware costs, technological advances in mining equipment and techniques, energy prices, and of course the price of bitcoin to name a few big ones. 

Here are some quick examples:Roof - 20-25 years tops (minus hail storms or weather damage, get insurance that covers it).

Long term is your plan to exit as you approach the 6.5MM mark to realize the $260,000 in equity stake you’ll have or to ride the wave and keep the $13,000 in cash flow?