Actually, with a VPN, you need to trust the VPN provider AND the site you're connecting to...
Though, I do believe that for connections from public WiFi it's somewhat of an improvement. It establishes a minimal security baseline of: "ok, we'll sell your data and let FBI snoop on you, but we won't inject trojans in your downloads and then hijack your webcam to create ransom-porn (though the FBI/??? might)".