Too scared and ashamed to dare launch a business

My question concerns business, or at least the vague and still tiny idea of a business! I’m not a coach, I’m a French journalist, but I would like to start a blog on a subject that could help people, and later possibly monetize it and create programs etc. I’ve been waiting for years to find the right topic: a topic that I know about, and that I really like. Yet, I don’t dare to take the plunge. I have the feeling that I am going to expose myself, put myself in danger, I tell myself “who do you think you are?!”, “you’re going to be ridiculous”, I feel ashamed and I have the impression that I am not smart or capable enough. How can I change these thoughts that are of no use to me and freeze me?
Thank you very much for your help!