I've got a toy language I've built at home for my own reasons. Lots of developers do.
The difference (especially in these modern times) between my toy and Rob Pike's toy is that Rob is paid by Google to develop it, hammer out the details, work out the bugs, and support it. As are the whole team Google dedicated to it.
Some languages get supported by volunteer armies (Lua comes to mind, last I checked), but TypeScript, Go, and Rust are supported / maintained by corporate money and it's hard to compete with that because a corporation can throw money at a language that isn't done yet while it's harder to get volunteers excited about a broken toolset.