Quite many I think...
In most machines there is no other browser installed. Most companies I mean.
And Edge is quite good, much better than old IE.
Home users most probably use Chrome or Firefox, but not all of then neither.
My experience with Edge obviously was not as rewarding as yours. I have attempted using Edge from preview to the latest consumer release. At this point Edge has finally allowed some of the extensions that IE had long assimilated and integrated. Only the latest release allowed me to F11 shift between full screen and everyday bars. Every day I find myself going out to IE to accomplish my task(s).
Worst change to IE is that MS seems to have abandoned any support for the browser - delays and lags and fails that did not exist before Edge was suggested - and heavily promoted!
I need to use Edge to access my company e-mail via office 365 but is uses a ridiculous amount of memory. Just webmail tab open and 600mb are gone. Firefox was also an option some time ago and that was around 200mb. The best feature of edge in my opinion is to support to trackpad gestures. Scrolling, pinch to zoom and back/forward with two fingers slide are great.
Don't pander to MS and talk about Edge. For one reason only, it should not be a part of the OS. Secondly, it is average at best.
But the bigger issue is that MS should be focusing on the OS and eliminating bugs and inconsistencies. What use is Near Share? It's really a joke right? I have 3 laptops in my house, never once wanted to share files between them. I have 4 Android phones and rarely want to share files between them. But let's assume that I do - hmm, yep none of my phones are running Windows, guess I'll just keep using SHAREIt.
At the moment I am using the latest version of Firefox. This afternoon I purged IE and Edge from the taskbar, not using why clutter. Was IE the only browser ever that allowed one to establish a series of sites as homepage easily? In my opinion the early releases of Edge were much better than the electron waster it is today.