Technically it's not illegal as in criminal, but it is a violation of the contract you're agreeing to in the form of the software license. And the macOS softwar

Technically it's not illegal as in criminal, but it is a violation of the contract you're agreeing to in the form of the software license. And the macOS software license only permits running macOS on Apple hardware (it can run in a VM, but the VM host must be Apple hardware). I understand that some of these EULAs aren't enforceable everywhere, in the form of consumer protection laws inhibiting what's basically perceived to be bullying behavior. At least in the U.S. consumer protection laws are weaker, depending on the idea that when consumers are bullied, they'll spend their money elsewhere. In a global market, asymmetric consumer protection laws aid bully behaviors. The countries were people are safe flaunting EULAs may have higher usage rates of software with unfavorable EULAs, rather than using alternatives with a more favorable EULA.