But the reality is much more complex than that. IANAL, but I do believe that they should likely avoid trying to monetize your data.
That doesn’t stop people who buy reddit from attempting it, but as I said before…if they do so egregiously, sue them.
In an ideal world your data should not be monetized. They might have backups but your data should eventually get phased out of those backups over time. It’s impractical for them to keep data forever, and old data is much less valuable.