Let's answer the real question, which is about you. Yes, you can build a successful startup as a designer. Someone else will be coding of course. But the CEO is

Let's answer the real question, which is about you. Yes, you can build a successful startup as a designer. Someone else will be coding of course. But the CEO is really the person with 1) the vision and 2) the drive to make things happen. Do you have both? Then you can start your startup.