If you're still wondering why Microsoft made Windows 10 free, just consider the latest stats: It's now on 75 million computers one month after its big launch, Windows corporate VP Yusuf Mehdi tweeted today. In comparison, it took six months for Microsoft to sell 100 million Windows 8 licenses, a more nebulous stat that didn't necessarily include actual installs. None of this is a surprise though: We've written extensively about Microsoft's desire to build a long-lasting Windows platform, and that starts with prioritizing the number of people running Windows 10 rather than mere revenues. Mehdi also divulged some other intriguing tidbits: More than "90,000 unique PC or tablet models" have upgraded to Windows 10; over 122 years of gameplay have been streaming to Windows 10 PCs from Xbox One consoles; and, perhaps most intriguingly, the Windows 10 store "has seen 6x more app downloads "per device than Windows 8."