The purpose of the drones is to spread the genes of the queen by mating with other queens and in doing so fathering the daughters of those queens. In essence the drones are the male reproductive organs of the hive. They don’t serve any direct advantage to the hive, but in an evolutionary sense the creation of drones is a major purpose of the hive.
Absolutely fascinating thread! 
And to be perfectly honest, after reading everything that came after my first post, I humbly apologize for that ‘snarky’ reply. :smack: