wouldn't you charge those people more before you start serving ads? Also wont a lot of those sorts of users be running ad block anyway? I'm mildly sus that this is the right way to go.

I’m not sure where you’re getting this notion that a paid service introducing ads is a bad business model. It’s been proven time and time again that it’s not. Spotify, Netflix, Prime Video, Hulu, the list goes on, all introduced ads and none of them saw any real backlash. Netflix cracked down on password-sharing and introduced ads in the same year and lived to tell the tale. Unfortunately people just really don’t realize how harmful ads are.