Decades ago, a guy came to me with a nutty business idea. He was filled with energy and enthusiasm. "It'll cut through the market like a thresher through a wheat field," (actual quote). He practically shouted, "like a hot knife through butter."
This sort of energy is contagious, but without a plan, it may not be productive.
I still remember a guy who used to work with me who came to me with a grandiose plan for a book he wrote based on a TV show. He had two data points: zero, where he started, and one appearance on one talk show as a result of one pitch. Drawing a straight line between the two points, it quickly reached infinity. Of course, very few things (even online) reach infinity any time soon.
The problem with bravado is that it forces you to suspend reality when making your plan. Optimism is self-fulfilling, bravado can be toxic.