Sometimes you have to eat.
I doubt anyone in the room really learned anything from this. The end result is mostly just the OP being out a pile of cash.
I'm not saying the OP handled it incorrectly, but I would have done it different.
And again, I'll just remind you that everyone who's ever worked for shit like gun or oil lobbying or any other number of harmful business activities have said the same thing. It doesn't make anyone smart, it makes them complicit in the terrible situation in front of everyone. Literally contributing to a worse world and less self worth for a dollar. End up living another shitty day while everything crumbles around you.
If more people stood up like the op, we'd all be better off.