Fast & Furious was simple in concept.
There had been several "reports" (assertions) that "more than 90% of the guns" used in the drug cartel violence came from the US. This was supposed to establish the meme that "the Second Amendment is killing babies in Mexico."
On actual investigation by people trying to verify this "statistic" it was found that guns of US origin accounted for a small fraction of a percent of the actual evil-violence-guns.
The FedGov, not wishing to lose traction on this, decided to "salt the mine" so to speak, by actively channeling guns into Mexico through known straw buyers. They monitored the purchases, and when FFLs called in to report suspicious buys, FedGov told them "go ahead and make the sale." Once the sale was made, no further tracking was done of those weapons.
It was to be only a matter of time before "American Gunz!!!" started showing up at murder scenes in quantities that would support the "90% of guns used in violence ..." meme.
What went wrong? US Border Patrol agent gets killed with one of those guns.
BATFE whistle blowers step forward. FFLs involved in the F&F buys step forward.
FedGov resorts to covering its butt. Internal documents and leaks make it clear they were not only willing to have kids die for this to work, they were counting on it -- kids had to die to achieve the objective.
Imagine their surprise and joy when Sandy Hook fell into their laps.
Or is that just a little too convenient?