If a person is placed in a position of power such as that of a politician are they naturally inclined to become 'corrupt'?

Worldwide politicians (alongside CEOs, powerful political activists etc) are questioned, belittled and fought against by those believing them to be corrupt or to be performing their job incorrectly in some manner. However, would these same people not be equally flawed if placed in the same position? Is the job of a politician one wherein additional power is so easy to acquire that it is encouraged? What defines corruption? Would your ideas, when implemented legally, be for the “greater good” or would you have been merely chasing ideas constructed by your ego?
I would appreciate any thoughts on the matter.