But longer sessions means more queries, which means more costs, which makes the problem even worse, right?

Only if the margins are negative. Yes, the cost to serve is most likely higher than Google's SRP, but I think the ads can be even better targeted and potentially have a higher CPM than Goog's.

What I'm saying is that I believe their ARPU could be higher than Google's, while what I think you're saying is that their cost will also be higher. I agree with that, but where we differ is that I think that while the margin will be lower, there is still potential to make a ton of money there.

They have a dataset of your deepest thoughts and questions AND a way to ask you stuff. Its literally the most valuable dataset on the planet