I often ask questions like this, and the most popular non-answers are, 1) think of the possibilities, 2) this technology is just getting started, so you can't judge it yet, and 3) unverifiable stories about some use case that is at best extremely narrow and may well be hogwash.

And when stating the imagined gains, the costs are always assumed to be zero. We know not to trust our data to a version 0.3 app, but somehow that's a fine thing to do with one's house or life savings.