Does there be many people flying online/flyin events in say USA or europe

Many people do fly during events.

 

The 'Westbound' or 'Eastbound' 'cross the pond' event normally has the most traffic.

 

https://www.youtube.com/watch?v=5VweINAQ97I

 

If you have a large enough group of you, you can normally persuade a controller to jump on to control at a specific time.