You should have boiled them down to the following lack of proper due diligence.  1.  

As @Terry Ouimet said...when you start off a project (or anything in life) from a bad/illegal foundation, it will never be right2) Yes absolutely we need to bring back or start anew with a proper green card/work visa program so we can get all of the LEGAL help we need in this country.

This likely means living in Louisville proper, depending on the job's location.

@Gerald Koonce Private lending from family members is allowed with proper documentation and compliance.

Gatlinburg and Pigeon Forge are both extremely strong right now , with most people overpaying in the years that you mentioned and simply not KNOWING OR CARING  how to properly run a top notch Air BNB. 

So, they got taken advantage of.4) They didn't do enough research on comparable properties before doing repairs - so went either overboard or slumlord, instead of properly Maintaining to the Neighborhood.The other challenge we encounter often is investors expecting perfection.

However, once a portfolio is properly diversified in a rather small number of different investments, the portfolio has reached maximum risk aversion by diversification.  

This would be my first STR so I also am personally interested in giving this business model a try to see if I do want to operate in this space longer term and want to do this properly. 

Grow a pair and dont take any crap. 

Investing in real estate means your money is backed by tangible property....assuming you do it properly.