I believe the most common case would be selling the user traffic, assuming the VPN knows who you are (through billing for example although given your traffic th

I believe the most common case would be selling the user traffic, assuming the VPN knows who you are (through billing for example although given your traffic their are a variety of ways even if you did an anonymous signup), they could then say "Hey Ben reads a lot of technical blogs and spends a lot of time on console.cloud.google.com, Triplebyte you should plaster him with ads because that will totally work".