The path to the TAM in your pitch deck starts at seed with a "killer wedge.". It's not a GTM strategy or PMF, but it sets the direction for both. It's a critical point that's worth thinking through deeply. NFX has been doing a deep dive into this strategy. Our findings below:.

This piece from @beller and @_dmuus_ gets at something important — the social, emotional, and market forces that push founders to optimize for the present instead of building for the long term.

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Every founder finds their idea differently. Some chase a lifelong obsession. Others, like Russ, build a system to test what fits. The key is knowing when an idea starts pulling you.

In Russ’s words, “I wasn’t trying to fix email attachments since I was four.”. But one idea kept resurfacing during the process: send a link instead of an attachment and give the sender more control.

That was the moment. We knew we couldn't not build it. Russ reversed engineered a system to lead to that idea + conviction moment. That moment, when the idea takes hold of you, is when things change.

Trulia was a combination of both. The rise of search, plus my own experience finding housing in the Bay Area led to the key observation. We can find everything else online. except find a place to live.

The idea is so critical. How do you know when it's right?. Often, we use passion as signal. You've been thinking about XYZ for years. Or you see a technology movement that you have to be a part of.

We often write about startup ideas at NFX and how important they are. As my colleague @JamesCurrier writes here, even a bad idea will take all of your life energy.

I asked Russ how he landed on the idea for DocSend. Usually founders tell a pain point story, or something of that nature. Instead, he used a spreadsheet and a point system. They listed ideas, scored them, and eliminated weakest ones.

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When @rheddleston interned at Trulia, we were fewer than 12 people. Years later, he built DocSend, which grew to $15M ARR and was acquired by Dropbox. While we were reconnecting on The NFX Podcast, he shared a memorable story:

The question for now founders is:. Which layer of defensibility am I building now, and which one comes next?.

Emergent theme: AI-agent networks and protocols. Agents will gain power by coordinating across domains. Protocol compatibility, shared action libraries—these are the seeds of future network effects. More on protocol and hub-and-spoke here:.

AI-native hub-and-spoke effects:. These platforms mimic TikTok-style distribution. Most content get no traction, but the few promoted by the platform explode in usage. Power-law dynamics create status and lock-in.

Memory + context becomes a personal utility network. Product gets more valuable as entire teams adopt it. The AI learns your codebase, norms, and patterns. Switching costs multiply with usage.

We're at the edge of a new defensibility era. Some network effects carry over, and others are being built today. Some possible developing themes:.

As you grow, strengthen your defenses. Your competition is likely just as competent. Focus on:. - Network effects. - Embedded workflows. - Personalization. - Expanding use or creating new value. These need intentional design.

In the early stage, your only real defensibility is momentum. That means nailing distribution + GTM. Clear brand. A loop that attracts users and talent. Thoughts on that here:. It wins attention. But it won’t withstand competition on its own over time.

We just published a new NFX essay on defensibility in the age of AI:. The core idea: In an environment this fast-moving, you can’t rely on a single moat. You need a layered sequence of defenses, deployed at the right time.

The AI era is producing growth curves we’ve never seen before. Yes, category-leading growth is a sign you're on the right track, but if you want to become the true leader, you need more. So, how do you know if you're accelerating toward category leadership or, heading to a.