Yeah, people will do something just for fun, to profit personally, or to spite someone

The moment they realize someone is making money off it, they start getting FOMO - humans are very loss adverse. No one wants to miss out on free money

But what if they had turned around and said, "fine, we'll start hiring you guys. You'll get paid hourly, but you'll have to do the proper paperwork, be given guidelines from corporate, reviewed on your performance regularly, and you might be relocated to undermoderated subs"?

Most of them wouldn't be into it - they don't actually want to work for Reddit, they just don't like feeling like someone else is sitting back and living off their work while they get nothing. The reality is, they're not doing a job, and they generally don't want to be (there's a difference between a job and work, especially work that benefits others vs a job protecting the cash cow)

When someone does a service for you, you act grateful and offer them lemonade and gift cards, you don't try to turn it into a job, and you sure as hell don't break their tools and ask when they'll get back to work