I haven’t found any sources on how many people world wide use UE.
Suggestions?
Hey
There is no official stats, but you can get a rough idea from these points:
- 25,365 users on the forums (as of a few hours ago)
- 4,800 github forks
- 15k developers registed on github
There is some more info [in this thread here][1], but no official stats.
Hope that helps give you a rough estimate though. 
thank you