Here’s an example of why getting the fastest Internet connection you can these days doesn’t always equate to a real-world experience.
This is the fastest Steam download I can muster on my 10 gigabit connection – which translates to just a little more than a gigabit downstream. Super fast, yes, but the reality is that you’ll never find a server that will give you all of your available bandwidth due to peering and capacity restrictions.
But with 10 gigs of bandwidth you can have multiple connections going on at once without any of them being impacted by the other.