What are you defining as good and successful?? ChatGPT has 800M+ WAU, that seems pretty good and successful to me (not financially but they have time).
AI companies aren't selling coding tools. Claude Code is not a coding tool! It's a tool that does coding, which is subtly different. The total addressable market for a coding tool is all developers, which is maybe 25-30M people worldwide, the total addressable market for people who need code written is potentially around a few billion or so, maybe more.