There's virtually no helium 3 on Earth, but that's not because we're using it up, it's because there was essentially never any really to begin with.

The moon has helium 3 on its surface so naturally that leads to the idea of mining the moon for the material. But there are no actual serious plans to do so, for one thing nobody knows how you would actually go about doing that. Besides there's practically no market for it, it's used in some fusion research but only a tiny quantity is required and that can be supplied with domestic supplies more or less forever, since it's possible to manufacture it from normal helium.