Gartner expects over 70% of global ad spend (80% in the US) to run through self-serve platforms where AI drives buying, pricing and reporting by 2028. Platform AI optimises for the platform's revenue, so its "spend more" suggestions are not neutral. For a Thai SME: keep a person reviewing ad budgets, use third-party measurement instead of platform-only reports, and concentrate tests on a few major platforms so results are easier to check. Junior staff can run AI ad tools, but they need experienced oversight.