Peope don't usually compare OpenAI with Dropbox, but Dropbox isn't particularly great with the free-to-paid converion rating. 2.6% is pretty bad, but they STILL manage to make money because what they do is pretty cheap on a per-user basis. They just host data, and most of that data isn't really used much. Also, I don't know if Dropbox is "that" profitable. All I could find is that their revenue exceeds their operating costs, but I don't know if that covers R&D or marketing, which they probably spend a LOT of money on.

Comparisons with YouTube and Spotify get thrown around a lot more, which convert around 5% and a whoppingly insane 36%, compared to OpenAI's measly 1%. And both YouTube and Spotify actually make a LOT of money on their "free" users, via ads. OpenAI has no monetisation beyond subscribers, and they're very bad at getting people to pay for their stuff.