Legacy platforms adding AI features are bottlenecked by their old architecture. Truly AI-native companies build agentic reasoning into the foundational control layer, enabling superior performance and interconnectivity between AI components, which creates a durable moat.

User stickiness for AI models is increasingly driven by the 'harness'—the custom prompts, workflows, and integrations built around a specific model. This ecosystem creates high switching costs, even when a competing model offers incrementally better performance.

To avoid being made obsolete by a frontier AI model, startups need a strong moat. The three most defensible moats are: 1) building hardware, which AI cannot physically replicate, 2) establishing strong network effects where value increases with more users, and 3) operating in a complex, regulated industry requiring human interaction.

As AI and better tools commoditize software creation, traditional technology moats are shrinking. The new defensible advantages are forms of liquidity: aggregated data, marketplace activity, or social interactions. These network effects are harder for competitors to replicate than code or features.

The enduring moat in the AI stack lies in what is hardest to replicate. Since building foundation models is significantly more difficult than building applications on top of them, the model layer is inherently more defensible and will naturally capture more value over time.

A key competitive advantage wasn't just the user network, but the sophisticated internal tools built for the operations team. Investing early in a flexible, 'drag-and-drop' system for creating complex AI training tasks allowed them to pivot quickly and meet diverse client needs, a capability competitors lacked.

To build a moat against large language models like ChatGPT, focus on features they will never prioritize. Build multiplayer functionality, a strong user community, and human-in-the-loop support services around the core AI. These layers create defensibility that a generic interface cannot replicate.

In the AI era, defensibility comes from building a complex system of record, not just a thin wrapper on an LLM. Companies with a 'thick application layer' that offers standalone value are unattractive for model providers to replicate, whereas thin wrappers risk being absorbed by the platform they are built on.

As AI makes it possible to replicate any SaaS application's features within days, the defensibility of a product no longer lies in its engineering complexity. The real, enduring moat is the network effect, which AI cannot trivially reproduce.