I very rarely have use for capacity beyond 40Mbps, or perhaps even 25. 4K streaming is as demanding as it gets. If 40Mbps is appreciably cheaper than 100, I'll take 40.
If your Internet connection can't handle video chat and streaming, then you're right to say you don't have a decent modern Internet connection, and it's holding back what you can do. Capacity beyond 40Mbps, though, is rarely of any real consequence.
(I mean this in the particular context of home broadband, of course.)
But the thing is that thanks to fiber there's hardly any difference price wise. So why not use it, when it's on offer?
Before that I had 100Mb up and down and was pretty happy with it. Large games could be a bit of a drag. Especially when GTA5 became available and I wanted to play it right now!
Once the JSON parses, that is ;-P