Companies don't purchase specific user data they purchase datasets.

Like reddit will says "we have x amount of user and here is what data we collect on them" you can access this data for $Y"

So and then those companies use that data to show you personalised ads or whatever and do a fuck ton, like and obscene amount of data analysis on it and your habits to see if it was worth the cost and will renovate with reddit the price to access their data.

So one individual user going weird won't do anything. But if you made a ton of bots and made them act weird you might be able to make the dataset worth less. But honestly probably not that much as they have tools to filter bots and stuff.