calling pre-built an easy- way out is not entirely true, I've got a pre-built rig, but, the problem is that My OS of choice, isn't legally able to run on custom hardware (due to EULA regulations, I know they could easily be bypassed and suffer nothing, I just prefer the peace of mind that I'm not doing anything that could potentially get me into trouble)
Also, even though it is pre-built, I know exactly what's in it and what to do if something fails. It really just depends upon your component knowledge. There are barebones systems out there, that comes with enough components and instructions that anyone with a screwdriver could build it and they would be as lost in fixing it as if they had bought a pre-built.