When you visit a website, it collects 70+ metrics about your “fingerprint”, by forcing your browser to render graphics, and do elaborate tests.
Then this fingerprint data is sold; to monetize your life, flaws, and addictions. As well as governments pay (or command) Big Tech to control you with custom propaganda.
There are many ways around this, but they aren’t so easy. It's not that fun to setup and use many virtual machines (like QubesOS). But now, you don't have to choose between privacy and convenience.