If we look at history, do the oppressed always become oppressors?
Mostly, yes. Christians were persecuted by the Roman Empire, then became conquerors of the world. Russians were oppressed by the Mongols, then became conquerors of Eurasia. Communists were oppressed by Tsarists, then became ruthless oppressors themselves. Protestants were oppressed in Europe, so they set sail to America and became oppressors of the natives.
Were protestants the oppressors of the native Americans? Many partook, for example the French.