The conventional wisdom in product development is to build for the widest possible audience. Cast the net wide. Sand off the edges. Make it accessible to everyone. This sounds reasonable. It's also, in my experience, the fastest way to build something nobody particularly cares about.
Every product I've built that people genuinely love was built for obsessives. Not for casual users. Not for the general public. For people who care deeply, irrationally, specifically about one thing. Forest fans who can name every player from the 1979 European Cup squad. Pub enthusiasts who have opinions about cask versus keg that they'll defend with their last breath. Parents in London who spend their Sunday mornings researching which farm in Surrey has the best lambing season experience. Japanese food devotees who can taste the difference between dashi made with rishiri kombu and rausu kombu.
These people aren't your average user. They're your best user. And building for them changes everything about how you design.
The obsessive advantage
Obsessive users are different from casual users in three crucial ways. First, they notice detail. A casual pub guide user might glance at the list and pick the nearest option. An obsessive pub enthusiast will notice whether you included the date the pub was established, whether you distinguished between Victorian and Edwardian interiors, whether your description of the atmosphere is specific enough to be useful. They'll also notice - and appreciate - when you get these details right. Detail isn't wasted on them. It's the entire point.
Second, obsessive users have strong opinions. They'll tell you when something is wrong. They'll argue about your choices. They'll suggest improvements. They'll care enough to send you a message at midnight explaining why your categorisation system needs a third tier. This isn't annoyance. This is gold. These people are giving you the most valuable thing a product builder can receive: genuine, passionate, detailed feedback from someone who actually cares about the domain.
Third, obsessive users share. Not broadly - they don't have millions of followers. But they share within their community. And within a niche community, a recommendation from a respected member carries more weight than any advertising campaign. When an obsessive Forest fan shares the Forest quiz with their group chat, it doesn't reach millions of people. It reaches the exact right people. The conversion rate on a niche recommendation is incomparably better than the conversion rate on a mass-market campaign.
Why niche beats broad
The internet changed the economics of niche. Before the internet, a product for Forest fans or Japanese food enthusiasts in London couldn't sustain itself because the addressable market was limited by geography. You needed people to physically show up at a specific location. The internet removes that constraint. A niche audience, spread across a city, a country, or the world, can collectively support a product that would have been impossible in the pre-digital era.
This is Kevin Kelly's 1,000 True Fans thesis, and it's more relevant now than when he wrote it. You don't need millions of users. You need hundreds - maybe thousands - of people who care deeply. Who visit regularly. Who share with their friends. Who feel a sense of ownership over the product because it was built for them, specifically, rather than for everyone, generically.
Oishii London works because it isn't a restaurant guide for London. It's a restaurant guide for Japanese food obsessives in London. That constraint - that specific focus on one cuisine, one city, one type of person - allows it to go deep in a way that a general restaurant guide never could. It can distinguish between different styles of ramen. It can recommend the best place for specific cuts of sashimi. It can have opinions about the authenticity of an izakaya in Soho that would be meaningless in a broader guide but are exactly what its audience wants.
Designing with depth
When you design for obsessives, the entire approach shifts. You stop asking "what features do most users need?" and start asking "what details would delight someone who knows this subject deeply?" The answer to the second question is always more interesting than the answer to the first.
For the Forest quiz, I didn't just include basic facts that any casual fan would know. I went deep - player statistics from specific seasons, transfer details, historical matches that only dedicated fans would remember. The quiz is hard. Deliberately hard. A casual football fan would find it frustrating. A Forest obsessive finds it thrilling, because finally, someone has built something that treats their knowledge seriously.
For Little London, I didn't just list activities. I included the specific details that parents obsess over: age suitability, pushchair access, nearby coffee shops (or in my case, hot chocolate availability), rainy day alternatives, exactly how long the activity actually takes versus how long it says it takes. These are details that matter enormously to the target audience and not at all to anyone else.
The authenticity requirement
Here's the crucial thing about designing for obsessives: you have to actually care about the subject. Or at least respect it deeply enough that your caring is indistinguishable from the real thing. Obsessive users can smell inauthenticity instantly. They can tell when someone has done surface-level research and called it expertise. They can tell when the product was built by someone who saw a market opportunity rather than someone who shares their passion.
I built the Forest quiz because I'm a Forest fan. Have been since birth. The quiz works because the questions come from genuine knowledge, not from Wikipedia research. The London Pub Guide works because I drink in London pubs. Oishii London works because I'm genuinely obsessed with Japanese food. The authenticity isn't a marketing layer. It is the foundation.
This is why I think the best niche products are built by people who are part of the community they're serving. Not because outsiders can't do good research - they can. But because insiders have the instinct for what matters. They know which details to include and which to leave out. They know what questions the audience will ask before they ask them. They have the taste for the domain, not just the data.
Build for one, reach many
The paradox of niche products is that the more specific you make them, the more shareable they become. A general pub guide is useful but unremarkable. Nobody shares useful but unremarkable. A pub guide with a genuine point of view - one that takes a position on what makes a pub great, that has the confidence to be opinionated - gets shared because it provokes a reaction. "Have you seen this? They didn't even include The Eagle!" is a better marketing campaign than anything you could buy.
Every product I've built started with me as the user. I built things I wanted to use, for communities I belong to, with the level of detail I would want. This feels selfish. It's actually the opposite. By building for myself - an obsessive user - I'm building for every other obsessive user like me. And obsessive users, it turns out, are the ones who make products succeed.
So build for the obsessives. Build for the people who will notice. Build for the people who will argue with your choices, suggest improvements, and share your product with the ten people in the world who will love it as much as they do. Build deep, not wide. The width will come later, carried by the enthusiasm of people who finally found something built for them.
