Why are so many people trying to sell Harbeths?

That doesn't account for the extreme rise, and it happened well before last year.

A number of years ago (10 or 15?) I read that when Harbeth started getting more popular they had to decide whether they wanted to upscale the company to meet demand or raise prices and keep their production capabilities stable.  They decided to raise prices.  I believe it was a John Marks post on audio asylum where I read this but I'm not 100% sure.  

You can definitely appreciate why they'd want to do this.  If they grow the company and expenses when there's a Harbeth fad they'll be in a tough spot when the fad is over.  If they see the enthusiast as their core customer rather than the fad follower they don't want to become dependent on the fad follower. 

That makes some sense. At least their product is worth the price. You may remember Talon loudspeakers. They did the same thing. They got some good press and immediately doubled their prices. Their speakers weren't good enough to justify those prices though, and with all of the competition, they started a slow death spiral, sold out to Rives, and ceased to exist altogether. I think Rives is gone as well.

The Harbeths at CAF sounded very nice one of the few that left me wanting to come back but gotta say the cost was a shocker for a speaker of that size.

I covered the whole show in about 4-5 hours on Saturday so could only note the rooms that caught my ear but not much extended critical listening in each.

 I popped in the larger deja vu room as well and that one did not register for me probably due to way out of any practical budget for me and not the sound I wanted to hear for that. Small rooms make it hard to demonstrate the full value of larger pricier gear for sure so not ideal for that.

The room was a nice size for the Harbeths though and I liked the sound very much.

So much competition at their price point though.

If you seek a very well made, nice looking,  good sounding product, the small size for the price point might actually be a selling point for some. I wouldn’t rule that out personally. But if you have room and WAF perhaps not an issue, then lots of competition at the Harbeth price points for sure.

There is a continuing assumption in audio that great speakers "should" sound good on any type of music. I am not sure that is totally true in reality, though it is a noble and worthy goal to pursue if you are building these

things.

..............and that assumption would be correct.