Disadvantages of a business plan

Business people write b-plans and then believe them even though in most cases the numbers are subject to a certain amount of 'softness' (guesses, estimates, etc.) that are used to prove the viability of the plan. If a b-plan is being used to get a loan or venture capital, there are often thresholds to even be considered, such as being a billion-dollar corp in 5 years (dot com bubble type startups). So guess what, the b-plan shows how that can happen. Once the funding is obtained, no one ever looks at it again.

Ask most startups if they have even looked at their b-plan after launching the business. It can be humorous to look at the 5 year forecast 5 years after launching the company or opening the store. If it is still there.

So the B-school answer is that you really need one to focus and manage your business. Maybe. You certainly need one to get funding from strangers, but after you get funded the usually goes into a file somewhere and life moves on.

Downside: They can take a lot of resources to craft, and in the end may not be that useful. Especially after paying for writers, consultants or others that may be helping with it.

They can also give one a false sense of confidence, as the entrepeneur often believes their own prose. That can make it hard to see the situation realistically.