They are opportunists, merrily digging along and hoping they will eventually find... something. Anything. Up until now they have found nothing much of value.
They specialise in spreading rumours of "great finds deep within the living rock". Recently they have come across "a large and strange device of arcane origin". What happens to these "amazing finds", nobody knows (perhaps they are put in boxes and stown away in the storehouse for eternity).
This ensures the contributions of wealthy donators, finances they direly need to survive.