I can't tell you how many times I hear men claim their expertise in business [and I purposely wrote "men"]. It's a constant and it's grating. Because as expert as you may have been, it doesn't always mean you will be an expert in the here and now. Failure to understand that has consequences - largely around innovation. Research backs me up on this:
"the negative consequences of self-confidence, which leads people to stick with and repeat the actions that brought them past success — and forgo exploring new ideas or methods that might lead to more innovations."