Yeah, except Milo hit this from a different (and completely sensible) angle. While the OP suggests spending years building up a free inventory system for all local merchants, the Milo guys realized that 1) A huge percentage of stores these days are big name stores, and 2) Those stores all use one of about 5 different inventory systems.

So they got at this problem by writing integration code with the existing inventory systems, and thereby got the data for a large portion of the market (nationally!).

I really like OPs idea, actually, but the Milo approach turns a 10-year plan into a 1-year plan, and if you can survive off the revenue you get from your 1-year plan, then you can use the excess to see your grand vision executed all the way through.

Clearly the Milo guys didn't go this route and instead sold to eBay (quickly!), but it's these kinds of "pre-pivots" that I think allow great companies to be built.

exactly.