What they've learned is the more 'busts' they make; the more $$ they get in funding next year to buy new toys and employ more people 'fighting the good fight'.
I'd almost sympathize with that mindset if it wasn't for civil asset forfeiture.
Don't forget the massive amounts of money to be made by colluding with the "bad guys". Collect double the amount if you collude for geopolitical purposes.
The primary purpose of the WoD is to provide jobs to drug cops. The DEA is aware that if drugs become legal, there will no longer be a need for a Drug Enforcement Agency.