Low confidence can result in the inability to make a decision causing the consequences.
The verb vacillate sums up this inability to decide. A person who vacillates alternates or wavers between different options or actions and is described as indecisive, hesitating, and not resolute.
A vacillating person may say, "I'm undecided" or "I'm ambivalent."
I am, hopefully was, that person. Hemming and hawing over most things right down to what shoes to wear. Also, I was accused of changing my mind a lot. Women are often accused of that, and, admittedly, are often guilty of being uncertain or wishy washy. This can be explained by a history of being denied the opportunity to make decisions.
Fast forward to 2018, and women are only holding themselves back, and most are not! I overheard a women describing her job to her son, "I make a lot of decisions all day."
The child said, "Oh, I would hate that, I can't decide what to eat for lunch."
She's the president of a large company, but one doesn't need to be president or even adult to make decisions with confidence. One just needs to have the confidence to realize whatever the consequences -- good or bad -- it will all be okay.
John Lennon sums it up with "Everything will work out okay in the end, if its not okay, it's not the end." (See also Optimism)