For any intelligent species to be considered objectively "successful", it has to keep asking itself certain questions:

• How do we ensure that we propagate beyond our home?

• How do we ensure that we don't self-destruct?

• How do we ensure that the products and evidence of our existence survive us in the event of our extinction?

And, to a lesser, more subjective extent:

• How do we ensure that no member of our species has a miserable existence?

So far, humans don't seem to be doing much of any of these.