You could make the same argument regarding typewriters and word processing software. I would think many more copies of word processing packages are in active us

You could make the same argument regarding typewriters and word processing software. I would think many more copies of word processing packages are in active use than was ever the case for typewriters. Word processing is several orders of magnitude easier than typing and as a result it's an incredible success. If a 3D printer allows you to pick a design from the web, click on the 'fab' button and start using your new product within the day, expect them to sell like hot cakes when the price drops.