There is one destiny of humankind, And that is to explore, Colonize and potentially rule the universe we know. While, This will probably happen in the future, I do believe that we should strive to have things explore space and discover new things while at that. Heck, We could even find a planet similar to earth, And there are likely billions of earth-like planets just in our galaxy, So we can progress in time to reach our ultimate goal, Which is to be known and be everywhere in the universe. Besides, There will eventually be a meteor that is large enough to devastate the entire population if it hits earth and our sun will eventually became a red giant, Most likely swallowing earth up. It isn't because it is our privilege to explore space that we should do it, It is because we will need to in order to continue living.
Humans are not required to explore the universe. And, contrary to popular belief, there is actually enough room on the planet to support more people than it currently holds. The problem is the unequal distribution of natural resources. Our foremost responsibility should be to fix the current social state of humanity and share what we have before we expand the human race. The more humans have, the more humans fight over.