text: why write a business plan for a dynamic, changeable business?   only as a road map, not necessarily to be followed.  in my experience with business plans, their main benefit is to help you think through the business before you start. it forces you to research the market, to know what to expect, the obstacles you will face. it is one thing to say "i want to start a clothing store" and another to be confronted with the realities of how to find manufacturers, how to get your clothing line to the stores, how will you compete, the question of production, the finances you  will need, etc.  the trouble with business plan stems from the assumptions you will make -- especially in the financial section. one of the common mistakes of entrepreneurs is to depict a very rosy prospect for their business -- which is fine, if it is true. they think they will sell this much; they think they can accomplish this much; they think they can do all the marketing plans they've thought of; they think that they can get the financing they want. then they start the business and find that the demand for their products is not what they anticipated; hence their revenue and sales figures fall short of what they assumed in the business plan.   business plans end up useless because of the erroneous assumptions made. more so with a dynamic, changeable business.  do a business plan mainly for the purpose of getting financing.