One sentence in the article states "The results are insignificant to explain the U.S. real estate boom occurred in the mid-2000s."

So, it just occurred to me if I rent a room in my house without putting any money into it THAT is an "infinite return" :)

You can also consult an attorney who might advise you on what to do with you rent while repairs are occurring if they take a long time. 

Remodel occurring in April 2022 and opening target May 15, 2022 with Airbnb.

Say for instance, you purchase a multi that needs a full gut job, you may very well intend to move into the property but its inhabitable until the rehab occurs.

I haven't had experience with HOA but have seen it occur in regards to zoning.

Is it common or reasonable to have in a contract with them that if breakage does occur with new items that they would be responsible?

Especially if you do it personally and with an LLC or two I mean... has it occurred to you that if you're going from having 1 mortgage, to having 6 mortgages (or whatever), in 1 year, a lowered FICO score is an example of the system working? 

If a housing recession of sorts occurred and damaged my job as a real estate agent, I could then dedicate myself  to property investing with my saved capital and personal connections. 

For the most part, I encourage all landlords to always continue with their standard rent increases yearly to keep with inflation and the CPI (2.5-5%, whatever is allowable) so that situations like this don't occur where the rents end up hundreds below where they should be.