I have always reported the rental income on Schedule E  ("Supplemental Income and Loss") form with the IRS and not schedule C because I hold title in  my own name, not in an LLC or S corporation. 

If you are in a market where  market rents do not rise every year you are in a poor investment market and should consider selling to invest in a market where your profits are not declining annually.If you are a hobby landlord you consider your tenant first when determining whether to raise rents or to supplement your tenants rent by a rising amount annually.If you are not raising your rents annually or are not able to raise your rents annually you are devaluing your investment and losing money.

This creates a modest priced rental and / or gives owners a way to supplement their mortgage payment (I'm a flipper - not a holder). 

Sometimes people care deeply about the interest rate; sometimes they want a certain amount of income to supplement their retirement - very possible since he's retirement age. 

I am a homeowner, we are retired senior citizens and we need extra income to supplement our social security.

I visited him over the holidays, stayed in his living room, and kept warm using a space heater to supplement the heating system.

But, I think it was a 3 day class.It was great and we both passed the exam the first time.The class gives you test taking skills, along with information they gather for what's on the exam.This was after taking the course and only to be a supplement to the course.

Ours happen to have central air ducted to the extra room but it could also be supplemented with a window unit or mini-split unit if needed for climate control.  

Any other ways to supplement that extra 20%?  

And they must pay for you to buy a supplemental policy if they for any reason do not have that policy in place(it can get cancelled by the insurance company, non-payment, what ever).