They have an unfortunate history of volatility in many cases.... unless you are willing to put down a more substantial downpayment, you may have difficulty finding a conventional lender to fund your vacation home/STR asset.

We're seeing a lot of volatility there right now where a murmur in a headline will make it shaky.Yes, I believe a severe crash is possible, and best to be prepared for it.

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. 

However, you are just starting this job, and the times and the markets are both volatile.

For a whole life product you can expect a consistent net IRR in the 3 to 5% range and with an IUL, with a lot more volatility, the average net IRR should be in the 5 to 8% with some years being way above, and some other being at zero. 

Think the demand will grow since: 1) BTC seems the last man standing2) Makes criminal activity and tax reporting issues simplerThink the biggest issue will be volatility of BTC. 

I used 15% (simple) because it represents a "middle of the road" return compared to the volatile S&P 500 index over the last 5 years.Would this tickle your investor's interest? 

You can chose to leave it invested in the stock market subject market volatility and mediocre returns, plus you have zero control over the performance of the stock market.

Of course, that is not repeatable all the time - it was a lifetime opportunity only for those who have the stomach to handle the volatility. 

I would not consider tenant B too much volatility and risk.