To which extent is C# System.Guid.NewGuid() safe for the following situation?

I'm building an app. Assume it is a messaging app and becomes as popular as whatsapp.

A GUID will be given for every message sent in the world.

There will be a problem if any 2 GUIDs of in the world are equal.

As of today 30billion!(official) whatsapp messages are sent in the world in a day.

I'm using C# (Xamarin)'s System.Guid.NewGuid method to generate GUIDs.

What is the chance for a 'problem' occur because the random numbers are not truly random?