Windows 10 benefits from an SSD. If you didn't configure your mac with a capacious enough SSD, you're probably going to need an external, which neither Windows nor Bootcamp officially support. Winclone is invaluable here, but there are hacks involving Windows to Go-- which technically requires a really expensive license.
I use Bootcamp to run a specialty CAD program, and a couple of games which either were never released for the mac (acquired from Good Old Games), or run so poorly on the mac as to invite desperate moves. Apple loves to deprecate libraries, and Microsoft loves to keep them around. I have some old hardware that won't run on the mac, but will on the PC (a really old, but really big graphics tablet, for instance)
I don't know if running a virtual environment will solve my performance issues, or let me use ancient hardware, though it would probably let me more easily exchange data-- windows can't see apple drives, and macos can't write to windows drives. I could probably buy third party drivers to enable this (the windows viruses probably have custom drivers by now, so arguments from the sandpoint of security are iffy). Right now thumb drives work nicely.