Whether you are on your home network or not, your are still connected to a public network using a browser that just by its agent string can provide a host of information. The point of a VPN is browsing privacy. Don't consider the internet private and any history only local to the browser your are using as it's anything but.
Using a VPN, your internet traffic is also encrypted and you'll be sitting behind a reverse proxy that not only masks your activity, but can also change the browser agent string making it look like your are using a specific browser when in fact you are not.
NordVPN takes this one step further by adding malware endpoint protection to secure the session completely.
Still think you don't need a VPN ? Surf the internet without one, and you'll be surprised at just how much of your fingerprint you will expose without even knowing it.