Hello, i don’t know where to write, so i write here.
I get stack with the problem of installing Epic Games Launcher, and i solve it. And i think what you can fix it.
Here is the steps i do to fix it on my MAC:
Get sure that you haven’t got any folder on your MAC, on my it was /Users/Shared/UnrealEngine
If found folder, delete it
Click on launcher
Wait wile it downloading and installing updates,
When installed i close the launcher(because it start reopens)
Open folder /Users/Shared/UnrealEngine/Launcher
Click on launcher and it works.
Now i can use it normally
I hope it will help you fix this bug. And as far as i saw launcher reopens from *.dmg. In my opinion this is the problem.