I don’t know where to start with this one, the author of this scheme has either a lack of basic finance knowledge or is hoping to find homeowners or students of similar stature. They are playing with numbers here to make the deal sound feasible, it’s not unless you can find a property owner willing to finance at less than 1/2% per year.
Your example of the 20 1-year notes equates to paying 10% on $25k and 0% on $475k for the first year and so on. Do you think anyone would accept those terms?
If you rewrite the two options in appropriate form here is how they compare:
Example 1) $500k, 20yr, 8%, Payment = $4,182
Example 2) $500k, 20yr, 0.0445%, Payment = $2,197
Sorry, just one more point. To put the response into terms of the original post. If the property owner is asking too much ie. $500k for their property and you offer this deal as originally presented you are effectively offering the property owner $263k for their property.