I feel I should comment in favor of the people building uber builds.
First, we're all in the same boat. They're not buying Macs, they're building computers - they are one of us. If they pump money into their DIY, and they're supporting computer vendors like you and I do, then they are helping promote our trade, our hobby, our passion.
Hmm. It's a plug-n-play hobby from what I see on most "help me build" posts. Now, if someone wanted to spend a certain amount of money with custom cooling loops, case mods, etc., I would say that is a hobby. It's probably like the difference between someone who gets expensive rims for a showcar versus someone who gets expensive lightweight rims to improve racing times on the track.
You can learn just as much building a $1k PC as a $5k PC. It's not the parts but what you do with it. For example, learning how to hook up SSD+HDD, raid arrays, watercooling, overclocking, etc.