Absolutely untrue by any metrics or semblance of study. People overestimate how unsusceptible they are to marketing. Marketing doesn't only work if you see an ad and click on it. It's after seeing hundreds of ads, that you start internally building a perception of a brand as whatever they market as (expensive, value oriented, fun, serious, luxurious, splurge material, etc.) Then the next time, maybe months after you've seen any such ad, you need to buy an expensive, splurge type gift for someone. If you remember the brand then, the marketing has worked.

That kind of stuff is absolutely worth the cost of ad spend online