I get that $500/t seems like an absurd price, but honestly that's not wildly out of line with what the cost of emissions likely are
Even if we eliminate ALL emissions, we will also need some degree of DAC in the mix. You don't fix an oil spill by closing the well. You close the well and then cleanup the spill. And if you wait to develop the technology to clean up the spill until after you closed the well, you've fucked up. It's too late.
There's a presumption in this kind of publishing that money spent on DAC necessarily is being pulled from other projects. If that's true, that's a disaster. But these DAC projects ALSO have to happen. They just have to. And the first and second generations of the facilities aren't going to be very good -- neither were solar panels.