OpenAI spends about $700,000 a day, just to keep ChatGPT going. The cost does not include other AI products like GPT-4 and DALL-E2. Right now, it is pulling through only because of Microsoft's $10 billion funding
True. They could close it off to the public at any time and only offer a subscription service.
However, they are probably afraid to do that for fear that they will lose out to competitors. Offering the service for free was the key to their popularity and bringing AI technology into the hands the average users. If they cut that off, someone else will quickly take their place.