One of these days.... The Rise of SaaS stocks

I totally understand why SaaS stocks are ripping and continue to be a big name and mover in markets. They are online, they are easy to reproduce, and all you need is a great sales team. But, one thing I am thinking about is valuation. At what point have they become detached from reality and at what point is it easy for a competitor to take away market share. For now I am just watching, but they are on my radar as they continue to climb. I think they have higher to go before the mania really begins. After that, I think volatility will enter.