Why do people use Macs for content creation?

I have always wondered why someone would purchase a Mac for content creation when the same software runs on Windows. I finally wanted to ask this question when watching Meshuggah and Wintersun recording in the studio and saw that they were using Cubase with Macs. Why would you buy an overpriced Mac when you could buy a computer or even build one yourself with Windows as the OS that is cheaper, way more powerful, and etc that also runs the exact the same software such as Photoshop, Premiere, Cubase, Pro Tools, etc.