Kind of reminiscent of the gold mining days in California in the 19th century. The people who made the most money were the ones selling mining equipment, mules and horses and wagons, clothing, food, liquor, housing and sex.

On a different note, a newb question: I don't understand why more miners means more difficulty. Do they compete with each other somehow? I thought the difficulty would be just how hard it is to find a block and verify it.