I think I probably agree with everything in your post. I don't see any disagreement between us.
Of course custom cue makers who produce small quantities of cues need to charge a reasonable figure for their time and expertise, otherwise there'd be no expert cue makers. And so I'm certainly not saying that a $5000 price tag for such a cue is unwarranted from the cue maker's point of view. It's the only way he (or she) can make a living, and really is a reflection of their time and effort. I'm also not saying that this wouldn't be a high end cue. I agree with you 100%.
As previously mentioned, the error IMO is in ignoring playability, and suggesting that because these cues are particularly expensive, that other cues CANNOT be considered "high end", either because there are too many of them, or because they are not expensive enough, regardless of how they play.
As per my golf analogy, a Callaway or Taylor Made is still a "high end" club, despite being a production club, and costing "only" $700.