I speak to you.

If you're having a 1 on 1 conversation, addressing the other person as "everybody" is weird. Addressing the other person as anything other than "you" is weird.

Make sense?

So, why does it all of the sudden make sense to start using words such as "everybody", "guys", "ladies and gentlemen" when you're speaking to more than one person at the same time?

If you want to be viewed as an excellent communicator, and you would like more buy-in from the group you're speaking to, use singular words even when you speak to more than one person.

Use "Dear friend," even if you're communicating with more than one friend. Use "Dear colleague" if you're speaking to more than one co-worker.

It'll make a huge difference.