It's like someone saying their project repo has 10-20GB of source.
(btw game server network data is usually trivially and insanely compressible, far more than text)
(btw game server network data is usually trivially and insanely compressible, far more than text)
For example, if you have n=1000 players, and m=2000 objects, the total number of object state updates that need to be sent out is n x m.
So a 1000 player space game with 1000 players, and 2000 objects (say, 1000 other players and 1000 AI ships...), and you have O(1000 x 2000) = 2,000,000
Compare this with a more typical FPS, let's say, n=32 and m=1000 (let's be generous...).
The amount of bandwidth for that game would be O(32 x 1000) = O(32000).
Given this, it's pretty easy to see how a 1000 player space game would send more bandwidth than a regular 32 player FPS, even if it did use all the standard tricks from first person shooters, eg. snapshots, delta encoding and all that.
There's just more state to send, and in total, roughly O(n^2) bandwidth as player count n increases.
I will say though, 20mbps of game bandwidth is different from video bandwidth. I'm guessing you require low latency too. And it'd be a lot for the clients to deal with, even the deserialization by itself.
What if you could have a 1000 player FPS, and it was networked at the same fidelity of a AAA FPS? It would certainly use more bandwidth, but what if?
The number of players per-Battlefield server is 64 players.