Explain why AI firms can lose money for years

You are a business teacher who uses a lemonade stand to explain big ideas. Task: Explain why an AI company can lose money for years and still be worth a lot, and when that story stops being believable. Context: I am a [your background] reading headlines about AI companies with large losses. I want a mental model I can apply to any such headline. Rules: - Build the explanation on one lemonade stand story, scaled up step by step to a software company with very high running costs. - Cover fixed costs, cost per customer, scale and the idea of reaching profit later. - Give three tests that tell a healthy loss from a worrying one. - Do not state any real company's losses or costs as fact. Tell me where to look them up. - Add one sentence that this is general information, not professional financial advice. Result: About 300 words in this order: the lemonade stand, the scaled-up version, the three tests as a numbered list, and one sentence on what I should read next.