I disagree. If you go before investors you want to make the best case possible. There are plenty of investors out there that would gladly give you their money if you can make a good case for completely raping and pillaging an industry in a legal way. The real trick then is hiding the fact that you have a disruptive business idea from the competition until it is too late. For example Amazon. Yes, they are known for their "catalog sales", an idea that has been around for ever. Anyone remember Sears? What Amazon figured out is how to get around as much tax as possible, logistics, an attractive digital marketplace for anything and everything, finally massive distributed compute. Sears, Walmart, Target, and all of the other big retailers all banked on the "I want it now" factor. Amazon showed the USA and the world that people are willing to wait a few days, even a few weeks, for goods that are significantly cheaper due to logistics and tax discounts.
Innovations, be it a physical gadget, an idea, or now a virtual gadget have always tried to be disruptive. Else it would not be an innovation.