Why use consultants?

A really good question with many angles, some of which I've listed below.

Quality and speed does not have to be opposites.
- NMMA   

Some good reasons for using  consultants: Often heard reasons for using consultants: The real reasons for using consultants:
  1. They like what they do.
  2. They (may) have experience from many other projects.
  3. They often have a network of knowledge to back them up.
  4. They don't complain about working hours.
  5. They're expendable.
  1. We need everybody inside to stay friends.
  2. We need flexible staff.
  3. We need specialists for this particular one-timer.
  4. We just don't have the time ourselves.
  5. They're expendable.
  1. You can always blame the consultant.
  2. You can tell your boss, that you have experts working on a solution.
  3. You don't need to plan. Leave that to the consultant.
  4. You can stay in control and boss the consultant around.
  5. They're expendable.