6 times? My reading of these prices is that it's 45x more expensive (for 8K) and 90x more expensive (32k)
The title compares GPT3.5 (not ChatGPT) with GPT4. Although the question is: If ChatGPT can do almost anything GPT3.5 can do, then why is it priced almost 10x less? Is it because GPT3.5 is less "censored"?
ChatGPT is GPT-3.5; with specific fine tuning / chat-oriented training, and without customer fine-tuning (at least, currently) available. It’s the particular GPT-3.5 interface that OpenAI wants people to preferentially use, so the price structure artificially encourages this.