When you sign up for a plan that is advertised as 1000 Mbps, you are essentially buying a line that's 1000 Megabits (Mb) not Megabytes (MB). We are usually more familiar with MB as that's commonly used to measure file sizes.
Whether something is in “MB” or “Mb” makes a lot of difference. In other words:
8Mb is approximately 1MB.
Or 8Mbps is about 1MB/s.
Or 1,000Mbps is about 125MB/s.
Thus the speed of your vps network 100 MB/s is a connection of 1000 Mbps.