This is a exactly a case in point why people decide to pay OpenAI instead of rolling their own. I'm non-technical but have setup an image gen app based custom SD model using diffusers, so not entirely clueless.

But for LLM I have no where idea where to start quickly. Finding a model on a leaderboard, download and setup then customising it and benchmarking is way too much time for me, I'll just pay for GPT4 if ever need to instead of chasing and troubleshooting to get some magical result. It'll be easier in the future I'm sure when an open model merges as the SD1.5 of LLM