I regullarly erase DVDs though, I sometimes burn them in order to watch them later but other times it's like "OK, I downloaded this but I ain't gonna watch it anymore/anytime so..."
For a huge collection like that, lossy will do fine. All the MP3 bootlegs/sources that we offer here in U2start as of today (excluding the 2014 and 2015 ones) are around 150GB in total.