5+ years of experience in adtech, on the advertisers' side mostly. By far the largest surprise for me was the amount of efforts that went into denying payouts to the publishers. That went anywhere from designing terms that reduces the likelihood of payouts to straight up fraud (ie. double accounting, scrubbing conversions, ...). Ultimately I think a lot has to do with greed: publishers simply expect too high of a payout for these clicks, and advertisers do not want to see the traffic go somewhere else so they align with these expectations. They are then caught in this unsustainable price war with competitors and resort to fraud to keep going. IMO the #1 issue with this industry is one of credibility.