I fully agree with what you just wrote. However, as it has been written here many times, the interior of the S is nowhere as luxurious as other $100K cars, it rattles, build quality is not to par, etc. While I can see someone taking a 10% incentive to pick a 3rd choice of colour or a car slightly different than his first choice; I do not think a 10% or $10K incentive is enough to push someone to choose a car as radically different as the S.
When I moved from the G37X to the Leaf, the monthly lease went down $35/month. I did not switch to save $35/month and move to a smaller, far less luxurious car. I switched because I wanted an EV. I think this is the same motivation for the buyers of the S.
Ok, now I'm driving a Volvo company car, when I retire or get fired, whichever comes first,
I'm back in an EV.