I think that's one perspective, but it's not the only one. What if you buy the best stuff and still invest the time making it all work? I think this is a lifetime build for MPH (ha ha just realized those initials are miles per hour!). There is nothing wrong with elbow grease and creativity, but it's not going to satisfy you if you wanted the best of the best. There is a lot of engineering and ingenuity in those parts, and many are just plain amazing performance wise. The thrill of not having to make due with stuff is really nice too. When you open the box on that amazing part and it is beautiful, sexy and bolts right in with all the loose ends resolved - that is at least as fulfilling as making it yourself IMHO. Once you get down to it, a rat car may beat a Ferrari to the finish line, but it still ain't a Ferrari. After all nobody ever bragged about beating a rat car in their Ferrari right?
I'm a little of both personally. But I can certainly see how it would be awesome to have built a bike that is as good as it can be.