This is a decent summary of some of the possible dirty dealings VPN companies are doing to make money: https://www.techuseful.com/hola-vpn-and-nordvpn-partners-

This is a decent summary of some of the possible dirty dealings VPN companies are doing to make money: https://www.techuseful.com/hola-vpn-and-nordvpn-partners-in-data-mining-bot-network/ https://www.techuseful.com/hola-vpn-and-nordvpn-partners-in-.... Not sure how much of what was in the article was eventually proven to be true, but it does highlight a few possibilities. In short, they can either spy on your browsing history and sell your data or they can hijack your bandwidth and resell it to shady people and you inevitably become part of some botnet.