The energy content in fissile material means that it is worth six times its weight in gold. But its monetary magic doesn’t end there: fissile material has the Midas touch. In other words, fissile material can not only generate revenue, but can keep generating that golden revenue time after time after time.
This struck me as quite significant in terms of space colonization. If you are going to make space colonization work, you need an economic basis. This could be a way to do that.