dark magic truly corrupting or just fast power

after a bit of thinking i got to wondering how many times in any media or story is dark magic itself a actual corrupting force. is it truely a force that twists the mind of its user. or is it just a fast power source. as many of shown often dark magic gives some power very fast a low level apprentice can out class a same level apprentice of a more regular school not always but often. so is dark magiic the very magic that fuels dark magic corrupt or is it just the fast power user gain.