I have a datacenter licence because it allowed me to spawn a lot of vm server 2012? Otherwise I would have to licence some other version of windows on top of the datacenter licence.
Yep, that's where you lose me.
$1000+ for 2012 Datacenter for home use?
And then your upgrade path is 2016 or 2019 Datacenter versions. Have you priced those?
How many VMs do you really need for working at home and must they be Server?
If they don't need to be Server vm's, you could just run Hyper-V in Windows 10 and licensed Windows VMs.
(Windows 10 as with other Windows versions (other than Datacenter) has a hardcoded limit of 1024 vm's, I'm pretty sure that is enough for you)
Legit keys are cheap for Windows 7 and 8, and still allow free upgrades to Windows 10 for the foreseeable future.
I just hate to see people waste money on an OS, that could be put into hardware