Surveillance capitalism isn't really about ads. Increasingly that data is being used to impact your life offline. It influences how much companies charge you for their products and services. It determines what version of their policies companies will inform you of and hold you to. It determines very big things like whether or not you get a job offer or a rental agreement, but it's also being used to determine even small things like how long a company keeps you on hold when you call them. It's being used to make people suspects for crimes. It's being used against people in criminal trials and custody battles. It informs decisions on whether or not your health insurer covers your medical treatments. Activists and extremists use it to target and harass people they perceive as being their enemies.
The data you hand over to companies is being used to build dossiers stuffed with inaccuracies and assumptions that will be used against you in countless ways yet you aren't even allowed to know who has it, what they're using it for, when they use it, or who they share it with.
Nobody really cares about what ads they get shown when they use the internet so companies like to pretend that that's what their data collection is all about, and they absolutely do use it for marketing, but the truth is that digital marketing is a smokescreen for everything else that your data is being used for and will later be used for.