You decry them as savages, when your own people still struggle and fight against the Universe, trying to bend it to your will.
You call them barbarians for adapting, nay, thriving, were all other races have fallen by the wayside.
The Necron once held dominion over the stars themselves, holding the entire Galaxy under their sway. They have been reduced to husks of their former glory, grasping at the sands that bury their tombs.
The Eldar were great and magnificent, accomplishing feats beyond any known race, only to be brought low by debauchery and infighting. They remain scattered and weak, never to truly rise again.
The Imperium once once as you were, spreading across the stars with the hope of unifying the Galaxy, and bringing peace to all species, only to be destroyed by treachery within. Now they are as you see them this day, their hopes and beliefs twisted, their dreams nought but a mockery made flesh.
The Orks have never fallen, never failed to spread among the stars. For them, the greatest battle of the Universe is won. They know their place in the Universe. They hold dominion over hundreds of stars, thousands of planets! Were all others have failed, fallen to infighting and corruption, they alone have thrived and expanded. Necrons, Eldar, Man, the Old Ones, all of them have failed to last as long as the simple Ork.