I don't think you have an accurate picture of how the nuts and bolts work for networking and the internet. You seem to think of your connection as (1Gbps -> Internet) when in reality there are several switches/routers in between you and your ending destination each with significantly less bandwidth than the total number of customers they serve. Bandwidth is oversold by an extremely large margin (rightly so). If you saturate your connection it has downstream effects that can degrade service for other users.