I worked in adtech. I built a simple ML system that detected signals of fraud on our network. When I reported my findings execs told me the group that was facilitating the fraud was our only profitable division. Soon after, our company went bankrupt. My final paycheck was months late.

Sounds exactly like my former employer ha.

IIRC our system wasn't even fancy ML - just finding known user IDs with identical timestamps over many simultaneous clicks / impressions on really diverse publishers.

Agency or client side?

I assure you the big brands CFO's take a huge amount of interest in what is spent on advertising.

In my experience the Sales and Marketing teams of any large company have the loosest restrictions on how they account for their spending.

Other dept;s like IT have to justify every penny, but Sales and Marketing not sooo much

I think there's a very loose belief that sales is how money is made, while they people that build and test products are pure expense.

I've seen it not just in the phenomenon you describe, but also in layoffs and restructurings.

Yes. Cost centre and profit centre.

Yes. Sales and marketing : "profit centers" . Ever increasing budgets.

Engineering , R&D, Manufacturing, Tech, Testing : "cost centers". Ever tightening budgets.

MBA, Beancouting 101

That's the issue - the CFO might care, but the staff actually delegated to spend the budget don't.