What's stopping an SPN provider from intercepting my traffic?

[Safing](https://safing.io/) has a tool that essentially monitors all your network traffic and blocks things from tracking you, as well as an SPN that essentially makes you the puppet master of all your connections.

As great as this sounds and as much as I'd love to use it as a set and forget type deal for internet hygiene, I can't help but be suspicious of a program designed to monitor every single packet coming from my computer.

How can I make …

can coming computer deal great internet love monitor packet privacy program safe single software