ChatGPT3.5 is not free for API usage. I would know this, I am making a project that uses ChatGPT. It costs money for every time I reach out to the API and get a response back. Sure, it is free if you go hop on the chat site and just interact with the bot, but API requests are not free. And I am working on a student license since my project isn't monetized, not a commercial one, which costs more.
Way back before this release, you had to setup your own API key, but the game was free. I spent 9 dollars IN A SINGLE DAY playing the game. They are not being greedy as you put it, but rather they are trying to find a way to monetize the project in a way that is reasonable to them and the end user.