Not really. Lots of companies have valuable data they sell and have been in business for decades just fine. It's even better for reddit because it's user generated so they don't even have to do anything. The users who left during the API debacle are not the vast majority of users which are generally casual and do not give a single shit about what happened, much as tech people like to think otherwise.
Again, this is a techie take. Lots of people for example use ChatGPT for personal therapy and guess which subs their training data comes from, r/relationships etc. Those trying to use them for other means are comparatively less frequent.
When I say casual, I mean youtube style comments where people just post memes rather than engaging, thoughtful content for whatever niche they're in. Which is essentially noise for training data.
Your interpretation of casual as stuff like r/relationships is itself "techie talk".