The point is Halo used to sell nearly 10 million copies (some in the series over 10 million) the original Halo on the OG xbox sold more copies than Halo 5 did and the Xbox One sold a lot better than the original xbox. The series isn't anywhere near as popular as it used to be and neither is gears of war. They are still big franchises but they are fading, it doesn't help that the single player portions have gotten really bad since both games changed studios but MP is what keeps those two series going and both Halo 4 and Halo 5 saw their player counts drop quickly.I’m not sure where you got those Halo 5 and MCC numbers but they are wrong, H5 sold 5 million copies by 2016 () and MCC 3.18 million by 2018 (VGChartz source but that’s all I could find). MCC sold an additional 2 million on PC much later. Even with margin of error there’s no way MCC did double H5.