So you do your games in Windows and your sensistive stuff in Linux.
That is exactly what we do at home. We play games in Linux too but nothing of importance happens in the Windows side. Microsoft could look over our shoulders while the kids are playing games but they won't get anything interesting.
Also - I prefer that my kids don't use the internet via Windows - adware, spyware, viruses, etc.
I've stopped with Win7. I won't ever upgrade to Win10 b/c Win10 offers me NO value. if at some point we have to upgrade b/c software just won't work with Win7 anymore then I would get very serious about firewalls and router rules blocking access to Microsoft.