I build custom GPTs but analyze: can custom GPTs generate income? Map custom GPT market: OpenAI revenue share, pricing, demand. Calculate: creation time vs. subscription revenue vs. OpenAI's cut. Show me the custom GPT reality: revenue share uncertain, OpenAI keeps most. Give me the GPT strategy: if building, focus on niche use cases. Include: whether custom GPTs are profitable, what OpenAI's revenue share is, and if it's worth building them.