Okay. So say you make an app that helps plumbers do their job well. If every plumber used it, plumber productivity would go up 50%, making life easier for all. It cost you years of your time and lots of money to make this great app, and you need a lot of plumbers to buy it to afford to continue working on it.

There's a big plumber app on the market already, but yours is way better.

How do you get plumbers to hear about your product?

1) The press? Uninterested. Plumber magazines or sites? Very low traffic - no way to scale.

2) Call or knock on doors of every plumber near you? If everyone did this, the spam would be unreal. Also inefficient and not scalable.

3) Referrals? You get some, but most plumbers aren't chomping at the bit to help their competitors. And because you started with so few, referrals are a snails pace and by no means exponential.

4) Organic postings and SEO? The big plumber app is way ahead of you. And 100 other worse apps clog up the listings. No one sees your posts.

See the problem? Without ads, you can't grow many many categories of genuinely valuable products. Even if no one else is advertising, you can't really grow without them.

This is barely a hypothetical by the way. I've worked with a dozen companies with similar situations.