investors tell you why they cannot invest, they are giving you free business consulting. Most professional investors have been entrepreneurs before and know plenty about growing successful businesses. When they tell you why they said no, they are dropping a recipe for success in your lap. They are giving you their best judgment about what you need to do to position your company for success. And this might be valuable to you. It is often the case that another pair of expert eyes can find areas where you can make your business plan stronger.
Of course, it certainly can be the case that the investors are wrong and you
might disagree with their judgment. If that is the case, go find another investor group. You might find the investment you are seeking. But if they give you similar advice that the first investor group gave to you, you might want to reconsider what you have been told.
If you see that the advice is good, you can improve that area of your business plan and then go back to the investors. They will be impressed that you were able to take their advice and that you were persistent enough to fix it. Most will