When you compare it to the other Sony models it does seem expensive, however I have no idea on the cost to manufacture a sensor and processor that can give such fast readout times, how much it costs to manufacture zero blackout etc, better build/weather sealing etc etc. I'm sure those things aren't cheap.
It's like the A7Riii vs the A7iii, on the face of it the A7Riii seems expensive, but again I've no idea how much more it costs to build a sensor with nearly twice the MP, the cost of the better EVF and viewfinder, again better build/weather sealing. Maybe when you start taking into account all the little things then the price starts to make a bit more sense? On saying that, the grey prices of the A9 and A7riii make A LOT more sense