It might not work.
A 5-year-old has no problems doing things that might not work. That's how kids learn to stand, walk, talk or do anything at all. And we don't put them down when they fail; instead, we encourage them and push them forward.
The industrial-education complex was designed to train humans to be cogs in their system who perform just as they are told. Years of schooling make us fear failure more than inaction. We don't even try anything unless we are sure it would work. And no wonder, we stop learning and growing.
Professional entrepreneurs and creatives cannot afford to wait until they are sure. They make assertions and take actions that might not work. They might fall, they might stutter, they might struggle, but one thing that they can't afford to do is to not act. We learn by acting, not by waiting for things to be certain.