Putting together a custom PC isn't a one-and-done purchase like consoles, and it requires a lot of effort to understand things like your needs, product compatibility, budget, and more. Additionally, you also have to track down and source individual components like the CPU and GPU before you can even get to the somewhat challenging part of building the PC. This entire process can be just as frustrating as it is rewarding, and it's certainly not for everyone.
Source: xda-developers.com