I think there is a lot of money to be made in building "human accessible" frontends to AI tools, so I'm not surprised that his ChatGPT wrapper product does well.

Setting up Midjourney, for example, is such a convoluted mess, where you have to create an account on another service (Discord) before creating a Midjourney account, then understand the different chat channels and figure out where the best place to use the app is (private DM with Midjourney bot.) And that's all before even generating an image! Even their website looks like someone's art project, not a cutting-edge image generation service: https://www.midjourney.com/