Yes, the knowledge component isn't enough.  

The ROI's tend to be in line, just less seasonality component.

All it does is takes your already calculated tax basis (again - your actual acquisition) and identifies some components of that basis that have more favorable depreciation treatment. 

For newly constructed, purchased or renovated properties and also retroactive generally over the last 10 years, building components are properly classified into individual units of property and accurate recovery periods for computing depreciation deductions.

Rehab must cost more than the purchase of the building.This was a layman's interpretation of the actual rule which is:The qualified rehabilitation expenditures exceed the greater ofThe adjusted basis of the building (and its structural components), or$5,0002.

But you are correct, often seller fi is a component of the financing.  

Whether you are a startup, you have started and ready to scale or you are nearing Cardone's level you need to look at 4 components and how you build the processes and systems. 1.

The Brrr strategy works best with a value add component that forces appreciation. 

“Everyone seems to want the best deal possible for the lowest price possible even if that comes at the detriment to someone else.”.

This is an often overlooked component.