Sometimes words fail, even when the entire point is discussion. Whenever this subject arises, there are often debates about the whys and what-fors, priorities and purposes. But I submit this as sufficient and eternal answer to all quibbles and caveats about the importance of spaceflight:
Credit: Chris Hadfield, NASA
If that doesn't move you, then you and I are separate and incompatible species. Forgive the brevity of this post, but these images are not merely worth a thousand words - they're worth every word ever written, and that ever will be written.