Derpestein said
I take that as they're all willing volunteers in the name of the Laughing Mare.
Or they were tortured to insanity. Idk.
It more has to do with the insidious influence of the Laughing Mare on their minds. They're willing volunteers, but they're basically mind-slaves, especially at lower levels (the converted townsponies, Revelers and Euphories). The slightly more lucid, truly willing cultists would be the necromancers (priestesses/priests) and performers, like the Jesters and the Harlequines.
The rest of the ranks are either reanimated undead or eldritch creatures like the Puppeteers and Grinning Worms, so there is zero chance of them being anything but loyal to the Mare.