I imagine if a person is doubting that big corpos are spying on us, then he is operating in a different paradigm altogether. I suggest this old but still 100% relevant article as a starting conversation point, bonus points for being written by an industry authority. Replace NSA with Google, Amazon, Apple or Microsoft etc. and nothing would meaningfully change.

https://www.schneier.com/blog/archives/2014/03/metadata_surv...