Fusion is possible, we even live near a star doing it right now! But there are so many challenges that combine to make it impractical for us to do on Earth. Ove

Fusion is possible, we even live near a star doing it right now! But there are so many challenges that combine to make it impractical for us to do on Earth. Overcoming them could consume so many resources most of humanity is forced back into the stone age, before seeing any positive output. Permanent, independent residence apart from Earth strikes me as a similar challenge.