Also, there is a need in the marketplace for a co-living PM company that doesn't charge too high of rate. 

Owners mistakenly ASSUME all PMCs offer the exact SAME SERVICES and PERFORM those services EXACTLY THE SAME WAY, so price is the only differentiator – and they often select the first PMC they call!

It isn't having paid off properties that offers security, there are still taxes, insurance, maintenance and management involved. 

We own 3 other rental properties that have a 6.5%-7.5% APR, and no credit card debt or any other high interest debt to pay off.

High property prices mean fewer people can afford to buy, so more people rent.

Tenant buyers that put a high option fee have almost always exercised the option and purchased the property. someone puts 50k towards the option I suspect that has a high potential to convert.. someone that does 10k much less..

Not to mention sky-high drama factor.

@Jay Hinrichs which BTW, 6% is high.

We bought a property that we feel is assessed by the our local government too high.

Your son is likely paying more than the property is worth, by definition, as the seller would almost certainly prefer a similar offer that was not subject to.