They have <a really expensive> infrastructure that serves 800 million monthly active <but non-paying> users.

Even worse, they train their model(s) on the interactions of those non-paying customers, what makes the model(s) less useful for paying customers. It's kind of a "you can not charge for a Porsche if you only satisfy the needs of a typical Dacia owner".

  They have <a really expensive> infrastructure that serves 800 million monthly active <but non-paying> users.

I give more of my data to OpenAI than to Meta. ChatGPT knows so much about me. Don't you think they can easily monetize their 800 million (close to 1 billion by now) users?