The investments don't pay off if they don't have (enough) revenue, but have you seen any indication either lab is not growing revenue fast enough?
However, we know that users frequently switch models/providers, and that models stay relevant for (increasingly) short periods release. I don't know what the training costs are, but I bet they're very substantial.
"if they stop training" is exactly the point I'm making. They can't stop training if the competition is still training.