Funny, I just logged on the forum to start a thread for this (soon to be) problem.
I have only base map and free modules + FC3 + Mig21 installed and it's 132GB!!!
I run a Windirstat on the main DCS folder and it states subfolder coremods is taking 90GB alone. Top subfolder in it is aircraft\f14 with 14,6GB, second place MirageF1 with "only" 8,7GB .
THOSE ARE MODULES I DON'T EVEN OWN and are wasting space on my drive with their liveries I don't care about!
Whole terrain nullmap for Caucasus is 16,8GB, a plane take away more space than the full map... What's going on?