Would they miss you if you were gone?
Perhaps something you offer is unique. If they can’t get that product or service anywhere else, what would your customers really miss? What benefit or outcome are they buying?
But let’s say you’re a commodity. You can create just as much differentiation and loss through superior service, ease of use, less down time and so on.
What your customers miss may not be tangible. It might be a feeling. An emotion. A diversion. Intangible, but definable.
Think hard about how you might answer this question. If you’re feeling bold, ask some customers directly for their feedback. Make sure the answer you get back is consistently highlighted in the way you market and sell.