And there's the issue - humanity is thriving far, far too successfully.
But we have to be clear that the thriving of humanity is not the same as having a sustainable human population living in complete and non-destructive harmony with nature. In fact, it could be argued that the two things are mutually exclusive (or at least, within the context of our traditional definition of the word "thriving" as being dominate, populous, numerous, pervasive, overbearing etc etc).
Humanity is thriving far beyond the means of the Earth to sustain the consumption of man and a rising population, each and every new human that expands our population, compounds the problem and makes it far harder to achieve balance within our ecosystem.
Maybe we need to re-define the concept of a thriving population to determine future prospects of sustainability and lifestyle improvement rather than the more traditional and very short-sighted definition that we tend to refer to.