Take

Worth a listen. His main point is that if you're a consultant you get to see, touch and own only very little, with no agency.

As some people notice, this is not necessarily still true; I've seen big companies use consultants to do what's necessary but impolitic, or throw impossible projects at firms that are too deep in to be able to do anything but attempt to deliver, or act as a wax paper-thin "source of recommendations", when they are more or less dictated up front and laundered. Some consultancies represent what's worst about business, but even good ones can enable dysfunctional businesses to misbehave even further.

Update: taken from a 1992 talk at MIT Sloan School of Management.