Is that any different than the trust we place in our ISPs?
It's not. Your ISP is probably selling your data, and your VPN may or may not do that too. Just assume everybody sells your data.
The difference is, when you leave home and you connect to a wifi, you start using another ISP. If you then lose the wifi and connect using 4G, you're using yet another ISP. If you use a VPN, you funnel all your traffic to a single provider all the time. In other words, instead of distributing the risk over several potentially bad actors, you concentrate it on a single one.
Like I said, that's a lot more trust that I'm willing to place in a single company that only essentially pinky-swears won't put me under surveillance.