Many people don't know that in addition to national fair housing law, states and municipalities may have additional protected classes (for example, in Austin TX we have local additions to fair housing that cover sexual orientation, status as a student, and others)There are resources from the national apartment association (and through many state and local associations) specifically geared to educating and supporting independent rental owners (usually regarded as having less than 100 units).  

Thats not to say that delayed gratification isn't an important concept, it is!

By no means is it get rich quick but given your pursuit of a PhD, I'm assuming your not afraid of a little hard work and delayed gratification!  

Most felonies are as well, especially those of a violent or sexual nature.

What if the prospective tenant takes the key and then drags some lady into the property and sexually assaults them? 

Living cheaply and saving a lot of huge, and something a lot of folks have a hard time with that, so props to you for living for the long term goals rather than immediate gratification.

Make sure you're continuously building your gratification-deferral skills.

If it's riddled with murder, rape, sexual assault.......or are they all minor drug charges....

All they wanted were instant gratifications that doesn't involve any work. we the investors today will face the same challenge of teaching our kids about investing and they only have one parent not the rich dad and poor dad .

If you need instant gratification then you will probably give up.