Mystery Ranch and Kifaru make a lot of money as government contractors. You can overprice your goods when selling to the Pentagon. Private sales are likely to be bonus sales. Also, both are made entirely in the USA and are strongly tied to local economies. Whether that is of value to anyone is another matter, but it does play into the high prices.
Kifaru is by-order, so no retail or distributors. Buy direct. Mystery Ranch might be the same. Considering that, you'd think they could be more competitive in the overall pack market, but maybe they don't need to be since they cater to government contracts and hunters who have never been known to be spendthrifts.
Again, I do not work for either company, and I do not own a pack from either company. I find this area of the pack market to be a bit strange and definitely intriguing.
I've never had a problem spending money on any kind of gear, whether it be hiking, bicycling, or audio equipment. They're high priorities in my life, so value comes from many angles. $600 on a backpack? Sure. $15K on a car? Not a chance.