It's just matter of a wrong perception: PC gaming audience is growing, but PC overall market, including home and office PCs not used for gaming, isn't growing, because except for gaming and high-end graphics and scientific uses, even low-end PCs reached performances high enough to last a long time before needing a replacement. And also for gaming, often upgrading a few components that may have become a bottleneck, is enough for most gamers, except power and graphics whores.