The only rational explanation I can come up with for the high cost is that it's a means of throttling use until you can acquire greater scale.

I've tracked Firebase with great interest since first hearing about it on HN. I'm disappointed by the cost, but I'm willing to give it a try and see how the value proposition ultimately stacks up.

In my use case, bandwidth is the primary cost concern with Firebase, but it's all text data (constantly dumped, so storage requirements are modest).