A Zero costs far more than $5k per bike to design, manufacture, test, warehouse, distribute, support and market.
Some of those costs scale better than others. For example, the cost to market gets less expensive per bike, the more bikes you sell. However, Zero is a mid sized company that has outside investors who need to get paid so there's a limit to how deep they can go into their own pockets as they try to scale up. (they're not public like Tesla and can't spend against their share price on the stock market)
And they already offer seasonal discounts and promotions. I got my 2017 DSR at a $3000 discount and they threw in $1500 worth of accessories.
Yes, list price on the bikes is expensive, and dealers don't have a lot of room to discount new bikes, but you're getting a relatively rare piece of seriously high technology with a much lower cost of ownership than a comparable ICE bike.
I'm on my second Zero and complaining about the price hasn't entered my mind for one second.