If you'd invested on demo day you'd be happy with current valuations, sure. But that just means the valuations are as high now as they are then. How many unicorns have repaid their investors in terms of dividends?
Altman is right that there's been a cooling off in 2015, and right that it's a positive sign - we may yet avoid a dramatic crash. But that doesn't mean there isn't a further contraction to come. We could just be seeing stagflation finally catching up to the tech industry.