Some, or all of the following reasons:* Because executives can't see the wood for the trees* Because executives don't know who they have in the organisation who could do the job, can't find them, or don't trust them, whereas consultants proactively promote their capabilities to clients with websites, glossy brochures, and produce detailed proposals and flashy resumes each time they pitch for work* Because consultants are always available, work to unrealistic deadlines, accomodate changes of scope without complaining (not to the client's face at least) and are more flexible than the resources executives have in-house* Because having consultants around makes executives feel more important and clever* Because executives don't like to make unpopular decisions without external support, or want visible validation that their decisions have been "independently" verified* Because consultancies contain talents that are difficult for clients to aggregate in one place themselves and which they could not economically justify employing as they do not generate the critical mass of work to keep those staff fully deployed (and interested)* Because using consultants keeps headcount off the books, they can be hired and fired at will with few legal challenges, they can be used for short-term projects but unlike most temps they're motivated and prepared to work hard, and come back for more no matter how badly you treat them* Because consultants sometimes work out cheaper on an hourly or piecework basis than permanent staff* Because executives want to cultivate networks with those consultancies they intend to join themselves in a few years timeI have used the term "executives" to refer to consulting buyers, but you can also read it as "senior civil servants".
