OK, so why shouldn't we invest in XRP if that's your whole premise? If we like the direction that Ripp!e has been heading in (I've personally been following since December) and we believe in the company/team/strategy, then why would you recommend against investment if the price of XRP is your whole model?
Several reasons. One is that Ripple Labs has different legal obligations to its investors than it does to people who hold XRP. Another is that there's no guarantee Ripple Labs' business model will stay the same over time. Lastly, there's always a chance that the Ripple network will succeed as a payment system without the price of XRP appreciating significantly. For example, if the Federal Reserve issues dollars on the Ripple network with no transfer fee, that could become preferred over XRP.
Also, I don't think anyone really understands what's moving the price of XRP. So the risk and expected rewards are essentially uncomputable.