16 GB is not by any means a large PS4 game - most typical "triple A" games, Battlefield, Far Cry, Assassin's Creed, even some racing games, are over 40 GB. Elite Dangerous no doubt keeps the size so modest because of fewer objects and textures than eg. the aforementioned.
And as someone mentioned you are seriously in need of a faster connection if that's going to take 14 hours. I think that's around 4 Mbit at the most, that was fast 15 years ago. I've been living in the poorest country in Europe for the last four years and even here (in the capital) I have a rock solid 100 Mbit connection.