I used to be petrified of public speaking, especially at high school when we had to give presentations to the class. These days people regret inviting me to meetings because I often take over

. Know what I mean? - they are thinking about a good way to maybe start asking about me considering perhaps developing some piece of software, meanwhile I already know and have the thing worked out already. So I tend to cut to the chase right away, there is nothing more fun than diffusing someones perceived bombshell before they even get started.
Fear of the unknown is the only reason I can attribute to phobias like this - these people are afraid of public speaking because they've never had to speak in public, or any time they have spoken in public, nobody asked them to. The more meetings I attended the more I noticed how people get nervous, to the point of stammering over practically nothing, the slightest challenge can send some people reeling. I can understand how people can be afraid of giving a speech in front of thousands of people, but to be afraid of speaking in front of a dozen people or less is just ridiculous. To fear that more than death is just crazy.
Maybe I'm a bit passive aggressive, or passive nervous, but the more someone else is suffering, the more confident I feel - probably not a good social trait, but when it comes to validating an idea or defending something/someone it's like walking into a knife fight armed with a bazooka. If you sit at a meeting and have to think of something to say, you have no place in that meeting. I often sit cringing when people struggle, and usually try and help out with a 'let me see if I got this straight' summary to give them time, maybe empathy earns us resilience, which is a nicer way of looking at it I suppose.
Anyhoo, fear of the unknown as I say, if people who fear public speaking were to speak in public a little - even if it's just telling a joke to a group of people, they'd probably start to prefer it to death.