I think WhatsApp potential value caps out at 50B or so. SpaceX potential value might be in the trillions (low probability). So while their current valuations might seem 'wrong', the long term potential value might be closer to your value judgement. There are very few large investors with a 20 year time horizon. I am not sure if that is a fault of capitalism. I am not sure another system of resource allocation would do better, do you?