Using the internet has long meant a trade-off between privacy, utility and cost. Users get free access to websites and apps while providing personal information that allows the technology business to earn huge revenues, usually from advertising. Advertising giants like Google and Meta cannot read your mind, but they can find out enough about you to target you with tailored ads, sometimes after sharing information about you with third parties. But the invention of brain-computer interfaces, including implants and headsets, has raised concerns that so-called Big Tech could some day be able to re…