I think it's better explained as "Valve is willing and financially able to keep tinkering with lots of things that will fail over a long time in hopes one of them pans out" than "Valve understands this exact set of assumptions of when VR will take off and is waiting for them to hit the trigger". One thing I do agree on is we don't know whether Valve is really "done" with releasing new VR products to consumers and, to be honest, I don't think Valve knows either at this point.