Tax Lien Sale Courthouse Steps - Really weird - Why did this happen????

[Russell R Massey]

Atlanta.
Referencing a small corner property, 45'x20', zoned Residential. Planning says nothing can be built there (well it could but it is VERY VERY VERY unlikely it would be approved per zoning). Long established residential neighborhood and used to be a corner store. Completely demolished and no slab left for 40+ years. Vacant for 40+ years.
In other words, anyone who buys it is buying the right to pay taxes on an unsellable lot forever. 
I had looked for the relatives of the deceased owner before with no success. 

It went up for tax sale Nov. 2023.

Somehow, a quitclaim was made from the sole heir just 5 days before  the tax sale - and recorded in the deed book the day after the tax sale.  

The tax debt was about $7k on the property. The property tax lien sale amount was $80,000 on the courthouse steps!!! So, they are close to $90k in. I own the surrounding lot and was the second bidder. Based on similar lots, it should have gone anywhere from not purchased to 3-9k. 

Can anyone clue me in to what the heck is goin on here? 
I will be glad to send you a $50 Amazon gift card for a really plausible theory. 

Prior Theories:
It could be turned commercial (no)
A residence could be built there (no)
They bought it to sell to me at a profit because I am the only one who cares about this. (Plausible for a $5k win. Not plausible for $80K+back taxes which gets up to $90k. If I would have paid more, I would have bid more)
They made a mistake and thought it was a different property (there are several with the same roadname but not the same Parcel - and this was professional who was bidding on several properties)

Can anyone clue me in to what the heck is goin on here?