Can anyone tell me why is it better for my privacy that all of my data flows through a 3rd party? A 3rd party who will now know everything about me (at least what pages I browse)
It comes down to trust. You already _trust_ your internet traffic to your ISP. If you trust a 3rd party VPN more than your ISP, then VPN is the way to go. You'll never be completely free of reliance on a 3rd party, except with TOR and the alike decentralized internet models. But, even those have caveats too
You also only need to trust this third party, rather than your home ISP, your work ISP, the ISP in the coffee bar you're working from today, the ISP that provides public transport WiFi, etc...