All you need is a startup business plan to get started

Yeah right, maybe in the 1950s. It used to be that all you needed to find funding was a good startup business plan. You could march right into a bank with that startup business plan and they would fork over a nice business loan to get things moving. Well times have change since then. Nowadays you can just have a good startup business plan, you need to actually execute on that plan.

What is a business plan worth and what does it prove?

There is some value to a business plan because it gets you thinking about the millions of little hurdles that you're going to face when launching your business. Keep in mind though that a business plan is a good exercise, but not a "proof". If the only part of the business that you have is the business plan, you aren't "proving" anything! In fact, many entrepreneurs waste valuable time writing a twenty five page (sometimes more) business plan just to work out all of the "details". Unfortunately, you have no idea what will work until you try it.

We'll let you in on a little secret-- investors are very smart! You may think you have it all worked out and have put together a flawless business plan, but investors know that you don't know JACK until you are executing on the plan and have paying customers. Everything in your precious little business plan is just an assumption (no matter how good it may be), until you put it into action. So put down that pen, pick up the phone, and execute on your plan!