That's very true, and just as everything tends to be cyclical in nature, so are those "cycles of corruption".
The fascinating aspect of the blockchain, however, is that many interesting ideas are being discussed in an attempt to better address such issues. And while corruption will always be lurking in the midst, I think we just might all be pleasantly surprised by the productivity gains that can be achieved, merely by attempting to minimize corruption to a fraction of what it is today, and also removing all the unnecessary "middle-men" along the way.
I can hardly imagine a world where all the "middle men" are going to just float off into the abyss, fractional I can accept, whole not so much.
it's already happening across many industries (except for those plagued by government-imposed barriers such as healthcare). As Milton Friedman once said, "If you put the federal government in charge of the Sahara Desert, in 5 years there'd be a shortage of sand."
But you're right in that saying "removing all" is way too idealistic a goal, so perhaps we can settle on attempting to weed out and "minimize the unnecessary middle-men".