Or maybe the aliens are all holding hands in a circle singing kumbayah?
The disruptions to equilibrium that we witness are almost always man-made. But there have been others, caused by new species, ice ages, asteriods, the Great Oxygenation Event, etc.
Alien civilization might be at equilibrium. Or, if we meet them, they may more likely be in an expansionist phase.
But I think a civilization that harnesses its conflicts - as we try to, with competing businesses, scientists, olitical parties, sporting teams - will have greater long-term success than a destructive, exploutative culture, by definition. It's not that competition is "good", but they we have aggressive aspects seeking dominance, and we are better off shaping them than having tribal warfare, raiding parties, etc which is more our natural state. And something like it is part of the nature of life itself.