I feel no obligation whatsoever to provide housing to strangers who will quite likely act in a similar or worse fashion.

I dont buy 4, 5 or 6% old fashion returns as the numbers do not consider the risk we are getting into, which is to have longer vacancy and bigger rotation.  

I mean really, after this virus, what investor isn’t going to appreciate good old fashion government guaranteed rent.

You can't talk about rights in a singular fashion. 

Then take into account the global economy also interacting in a similar fashion at the national geo-political level.... 

I believe 5% is arbitrary or part of their much larger context regarding diversification, as I frequently see figures like 5%-10% used when discussing the maximum amount of your portfolio that should be invested in any one stock, sector, asset, asset class, etc.Another thing to realize as well is that followers of Dave Ramsey and followers of BP seemingly approach saving and investing in very different fashions but both can work and provide growth and financial stability based on the the person and their situation.It's up to us to determine which school of thought, or combination of the two (or the countless others, for that matter) is the best fit for ourselves.

They wore fancy jewelry and clothing worth more than my rent. 

We maybe old fashioned BUT how about owning your own home free & clear.

So it comes down to good old fashioned homework eh? 

Maximizing profit is exactly what the Realtors, lenders and investors/speculators have done in a rampant fashion, and back to the original question posed by the OP- thats the root of the problem you speak of.