This type of quantum singularity - also known as "Jeff K. Foam" - sends out a practically endless stream of exotic matter. Navigating these fields requires all the energy the engines can produce. It is suspected that only a handful of these sources exist in the whole universe.
Exotic matter regenerates at a constant rate and a lot faster than other natural resources. Further, when harvesting it, one gets always the same amount of exotic matter; there is no skill for exotic matter collecting like for other resources.