As their revenue increases, your profit decreases. 

I guess it became red ocean(too many airbnb), and demand might be decreased, or permit issue?

My first advice is to start saving and decreasing your expenses.

Real estate investors should be aware that higher interest rates can drastically decrease the amount of cash flow they generate.

They just do it all wrong and I know in an 18 month to 24 month period I can increase rents $80.00-$100.00 a unit and replace a low class tenant base with a stronger, higher class tenant base, while at the same time decrease wasteful expenses that the previous owner was not aware of our was just giving up and wanting to get out.  

The risk of renting to those with non-traditional income sources is that those sources can dry up quickly;  someone who makes their living as a baby sitter as their only source of income can suddenly find their income decreasing quickly through no fault of their own if their "employer" suddenly decides they no longer need a sitter.

The muscle memory of working all the time (the american way) seems tough to unlearn. 

They meet again in December and are not discussing any potential for decreases, only holding steady or increasing.

On a positive note, rates are increasing and nation-wide, Mortgage applications have been decreasing in 5 of the last 6 weeks per mba.org.What this means for you is that competition may be dwindling a bit *check with your local Realtor regarding demand in your specific market.You're off to a solid start so I'd continue reading and check out some of the free resources on BP including the webinars, forums, local events/meet-ups, etc.

This puts all the risk on your family friend so they may ask you to come to the table with 10% in case the property decreases in value YOU'RE the one who eats it and not them.