Why should the release GPT-5 if GPT-4 is still at the top of all benchmarks? 95% of the population who are not techies will probably use ChatGPT anyway for everything. I think they are pretty much the leading LLM company in most ways.

It is all financially-driven. All of the AI companies are working on models constantly are are purposely putting out releases so they can be ahead of the game or have some nice news for investors in order to make sure their stocks grow.

OpenAI probably know they are ahead with GPT-5 as well and they are planning to drop it Q3/Q4 after Llama3 (which will maybe trump GPT-4), so they can be ahead again for the EOY earnings.