I had similar question as you and conclusion as OC.

My answer maybe abstract in some ways, but:

- something that requires network effects, e.g social media, even twitter with megahitler stuff is going strong. Even though twitter's base app model could be done in 30min by LLM;

- something that maps to infrastructure in someway. Good luck copying Cloudflare, residential proxy provider, established email provider or VPS with LLM in a weekend. Though parts of it are definitely easier;

- something that is a platform (adjacent to first point). Google's search platform, ads, docs, youtube, music, email, business tools, etc. Similar to Meta (seemingly half of the world's small businesses control their business with whatsapp) and others. Though parts of those platforms can be disrupted with LLMs;