> I don’t understand how they will grow to infinity.

You either have to be consuming faster than the queue is growing, or you are adding faster than you consume. There is no equilibrium.

If you are consuming faster than it is growing, at some point you'll consume all jobs, meaning your queue is sometimes empty. If you are adding faster than you consume, your wait time approaches infinity (tho in reality you'll fill up your queue storage first, of course).