Let's start with the two assumptions that
Government should be functioning in the best interests of their Citizens.
If there needs to be a subset of the group of Citizens, then Government should side with the one that benefits the most Citizens.
The Wealthy love their country enough to volunteer their own money to improve it as they see it. Do they necessarily have the same objectives as the two above? If so, then the Wealthy are not a corrupting force.
If the Wealthy use their influence to deviate the Government from the two above assumptions, then the Wealthy are a corrupting force. and should be examined closely with the second assumption in mind.