Even AC luminaries like Marbles has admitted to making purchases to impress people in the past (not trying to take Rob out of context, just referencing a very old thread- he's a very knowledgeable guy, one who's opinion I trust). I think some tweaks we stick with is out of our herd mentality. Now I don't mean this as an insult, and at the heart of it that mentality has served us pretty well or it would have been deselected by evolution. For example, I'm fairly cable agnostic- I don't doubt that the worst cable ever made could sound poor compared to the best ever made, but I've heard very little evidence of it. Nor does prices and appearance seem to correlate well with sound. Go ahead and feel free to impugn my manhood, my hearing, my system, whatever you like!

Still, I have spent more than I felt was strictly necessary "just in case", to counter that nagging worry that I might be "missing out", and to establish a bit more "cred" among my fellow audiophools. Ultimately I think we all do this sometimes without thinking. Again, if Marbles/Rob tells me a Z-Sleeve makes a big difference, I'm strongly swayed to hear that difference whether I want to or not (I'm not saying it doesn't, just using this as an example). I may even buy a few for my system even if I don't hear any difference.
Perhaps my current gear isn't resolving enough, I tell myself- I'll just keep 'em til I get gear good enough to hear the difference.
I love tweaks. And being very frugal, I especially love cheap/free ones. I don't mind dropping a few grand on speakers, a couple grand on an amp, or a grand on room treatments. But I ain't spending a couple hundred on a jar of pebbles or a magic clock!
Well, maybe on a
Sonicrock. 