Oh yeah, Saruman's pride ... the driving force behind his rise to power, and the cause of his ultimate downfall.... it's implied Saruman's treachery might have been because he was envious of Gandalf being chosen first.
Gandalf (on Saruman):
As a consequence of his pride and the awareness of his power and authority, Saruman became more and more ambitious, and wished for more power. His ambition shows in his word to Gandalf:"He is great among the Wise. He is the chief of my order and the head of the Council. His knowledge is deep, but his pride has grown with it ..."
Although he was considered the chief of the wizards order, some members of the White Council had more trust in Gandalf and his powers than they had in Saruman. This probably turned Saruman's pride and ambition into envy, and made him desire to do better than Gandalf:"But we must have power, power to order all things as we will, for that good which only the Wise can see. [...] Knowledge, Rule, Order; all the things that we have so far striven in vain to accomplish, hindered rather than helped by our weak or idle friends."
Saruman believed he was strong enough to use the palantìr for his own purposes, to give him advantage over Gandalf, and to gain more power and control through his knowledge of far away events.Being jealous and afraid of Gandalf he [Saruman] sets spies to watch all his movements ...
However, his pride didn't allow him to be enslaved by someone else. As Gandalf said of him:... The rock of Orthanc has withstood the storms of time, so there the palantìr of that tower remained. But alone it could do nothing but see small images of things far off and days remote. Very useful, no doubt, that was to Saruman; yet it seems that he was not content. Further and further abroad he gazed, until he cast his gaze upon Barad-dûr. Then he was caught!
Saruman wanted power for himself, and was not faithful even to the Lord of Mordor."He will not serve, only command."
Tolkien's conclusion:
... impatience, leading to the desire to force others to their own good ends, and so inevitably at last to mere desire to make their own wills effective by any means. To this evil Saruman succumbed. Gandalf did not.
