Protection from IP tracking, especially if your ISP doesn't do CGNAT. Of course there's a trade-off here between
a) your ISP (who knows your billing information) knowing which sites you visit, and any site you visit can correlate internet activity back to your household
b) your VPN provider knowing all the sites you visit
But a VPN, commercial or self-hosed, also won't stop fingerprinting. It changes your apparent IP address, but the rest of the characteristics of your device and browser stay the same.
a) your ISP (who knows your billing information) knowing which sites you visit, and any site you visit can correlate internet activity back to your household
b) your VPN provider knowing all the sites you visit