As someone who is not remotely as comfortable in a presentation setting in front of a crowd of people as I am one-on-one, one of my biggest issues is a lack of attention. It's pretty easy to see who isn't giving their full attention, and I end up immediately thinking about that instead of the actual presentation. I end up looking for someone who is paying attention and just start presenting to that individual to ease my way through it. And I'm at most working with ~30 people.

Can't imagine having to put up with it on a much larger scale and severity.