Some people naturally sound convincing. They have charisma, they find it easy to tell their story, they are confident, they can wing the presentation, they say that they consider themselves good presenters. They sound convincing, but do they convince?
Many of the people who fall in this category are not very good at reading body language. Maybe the buyer or investor on the other side of the table is (slightly) introvert and does not push back that much. Maybe if the same type of question comes back for the third time (after 2x the same sort of answer), the answer was not very clear. Maybe there is a difference between a great meeting with great energy, and a decision to buy/invest.
As a presentation designer, I have built up another type of self confidence: not being ashamed to ask again if something is not clear, even if it is the fifth time. If I don't get it, the presentation I am going to design will also not get there. Investors and buyers won't be as patient as presentation designers
Image from WikiPedia