The brilliant 6th century military strategist, Sun Tzu, is said to have quoted

“Tactics without strategy is the noise before defeat”.

Makes sense. Failure to plan is planning to fail. You may get lucky without a business plan but with so much at stake, it would be irresponsible to rely on chance. Besides, luck has a habit of deserting those who become too reliant on it.

Business is a risk and good businesses are great at minimising risk while maximising their chances of success.
 
Have you thought about how your business model will look like 3 or 5 years down the track? Will you still be a dominant player? What disruptive forces are at play and how will you address them?
 
Strategy development is about getting to sustainable profitability and involves understanding the business thoroughly, positioning for uniqueness, building internal capability and marketing aggressively to the right customer.