When you purchase a game from Steam Early Access, there's always a risk you take that the game you put down that hard-earned money on may not actually release in full. Sure, that doesn't always happen, but often enough that Valve has opted to issue a warning about Steam Early Access on the latest update to its FAQ on the same topic.
The update comes in the form of the question "When will these games release?" and Valve indicates that players should be aware that some developers may be unable to finish their games, for different reasons. Essentially, it means that buyers should always beware: you have paid for the project that you are currently playing. There's no guarantee that it'll be completed in the near future, or ever. And while that's unfortunate, it's the nature of the beast.
Have you ever been burned by purchasing a game from Steam Early Access? That's a prompt, not a real question, by the way. I just know you have. Tell me your stories. The good ones.