Given the huge cost of launching vehicles into space, and probably bringing stuff back from the moon, I’m skeptical that this will be a cost-effective project. However, figuring out how to extract and exploit off planet resources would be a huge step towards that staple of 1950’s science fiction - terraforming, i.e. creating earth-like environments on other planets. Still, given our amoeba-like understanding of how climate works, let alone changing it, terraforming will probably remain a pipe dream for the indefinite future.
Helium 3 is very light…it’s not as if they are going to mine gold or diamonds or some such..