Fifth, elements outside your planning or control can increase expenses significantly; tax increases due to budgetary shortfalls, insurance costs doubling due to natural disasters, tenant damage beyond what the security deposit will cover.  

Certain types of glue can outgass smell like natural gas for weeks causing nauseating and vocal complaints.

The Unilin 2g locking system is one of the most efficient ones on the market.I 100% agree the the subfloor/ underlayment/ substrate being attached to as well as how  it was attached to the builder floor(naturally we're not talking cement) is usually the problem in a failed installation. 

Some plumbers refuse to install the cheap water heaters, so they will naturally cost more.

Not necessarily a deal killer IMOAlthough it's against nature, the tree can be removed, the roots poisoned and there should be no damage to the foundation long term.Just my opinion 👍

On the other hand, natural hardwood floors are beautiful!

These properties do it through design, unique nature of property, and the "natural pools" available on the property.  

This is the nature of the business, you are not doing anything wrong from what I am seeing.

Some areas are getting hit hard with natural disasters, and their insurance premiums are sky high!!! 

They are attracted by nature, affordability and bang for the buck.