Well "they" don't manipulate me. I don't respond to adverts and I only buy what I need or want. I ask myself before any purchase, do i really want this?
As for deciding about me, who? deciding what?
You too are influenced by ads. Most people like to think they're independent and rational folks who aren't that easily manipulated. About half of people think ads don't influence them. That's obviously as plausible as the vast majority of people thinking they're superior drivers. Advertisers actually know people don't like the feeling of being coerced to buy something. That's why advertisement is much more subtle than that. It's not see X, buy X. How to influence people is a science which has been carefully crafted and perfected over decades. There's no shame in being susceptible to it as it's years of development and science versus what makes you human. We essentially don't stand a chance. Moreover, the more information people have about us, the less of a chance we stand. "...participants thought others would be influenced by the message, but that they themselves would remain unaffected. When psychologists looked at the results, though, it was clear that participants were just as influenced as other people. This was dubbed the ‘third-person effect’." See the first three links posted below for more on advertising.
It's not just advertisements though. We're constantly manipulated in many ways. Algorithms and bots decide a large part of our lives. What results you see when you do a websearch, what articles you see, what song comes up next, what ads are served to you and what videos Youtube suggests. Everything is carefully tuned to cater to your specific interests and needs to retain your attention the longest possible time. Here too does more information mean more well-crafted suggestions that serve the needs of those making the suggestions. Many people never even realize they live in a search bubble constructed by someone else for the benefit of someone else.
It doesn't stop there though. Companies you never heard of know more about you than you could ever imagine. They collect data from various sources and compile these into results. They score you and they rate you and how you do has a meaningful impact on your life. These kinds of companies end up deciding whether you're considered a trustworthy customer, whether you can rent a car at what rate, whether you're a big fish with cash to burn. All you might get on your end is a "computer says no" and you'll never know that it was your data and some algorithm that made this happen to you. See the bottom two links for some more information.
Big data is a very exciting field but it can be a great friend, but also your worst enemy. All these things are only possible because large datasets about you exist and many groups know a lot about you while you know nothing about hem. There's no way to win such an imbalanced situation. The best thing you can do is reducing the amount of data collected as much as possible even if it's not going to ultimately save you.
https://scottfenstermaker.com/third-person-effect/https://medium.com/@dahanese/advertising-works-don-t-believe-me-then-you-are-my-favorite-demographic-ebf6b1f2541ahttps://www.mediavsreality.com/mediavsreality/2018/12/6/advertising-doesnt-work-on-mehttps://www.nytimes.com/2019/11/04/business/secret-consumer-score-access.htmlhttps://www.fastcompany.com/90310803/here-are-the-data-brokers-quietly-buying-and-selling-your-personal-information