You were playing a game without paying for it. How did you imagine they were making money without pimping your data?
Unsarcastically, a lot of people believe user data belongs to users, and that they should have a say in how it's used. Here, I think the point is that Niantic decided they could use the data this way and weren't transparent about it until it was already done. I'm sure I would be in the minority, but I would never have played - or never have done certain things like the research tasks - had I known I was training an AI model.
I'm sure the Po:Go EULA that no one reads has blanket grants saying "you agree that we can do whatever we want," so I can't complain too hard, but still disappointed I spent any time in that game.
I can understand that people believe this, but why do they do? Nothing in our society operates in a way that might imply this.
Off the top of my head I think GDPR in the EU might have something to say about this. I don't know if those protections exist anywhere else or not.
In the US, people get very upset about things like traffic cameras, and public surveillance in general. Those are usually data-for-punishment vs. data-for-profit (...maybe?), but people here resist things like data recorders in their cars to lower car insurance.
At least to me, being unhappy about Niantic's behavior here does not seem the least bit unusual.
If they just keep the positional data and location information like the video gathered without linking them to a player, it’s perfectly fine.