However, the snake oil part is the implication that paying more will somehow give you more functionality.
And there’s the whole “more is less” conundrum. High-end equipment is by its very nature less purchased and less examined, less reviewed, than less expensive stuff. Small-batch manufacture has quality-control problems that mass-produced items don’t. And so on.
There is always an opportunity cost. So the “diminished value” would be the things you aren’t buying with the money you wasted on an overpriced item.