I'm not justifying its valuation, but your argument is fallacious.
It doesn't seem that difficult to cash out at least few billion with that kind of volume.
What? Where on earth did you get that? Because his girlfriend bought one for $10 from the story, you've now created the idea that she did the math, considers it a worthy investment and knows the full market cap? What if she just wanted $10 of entertainment for the evening by buying a silly coin and talking about it? That seems like a solid investment to me, much cheaper than a movie for example, and does not imply that she thinks the full value is worth $10T USD. She could easily be a rational investor who thinks no such thing.
A market composed of numerous entities trading large sums of money is a much better system to decide the price of something. One person making a single purchase for unknown reasons is not a "market".
- Ripple offers blockchain software aimed at banks, who use it for transaction settlement. These banks will use a private blockchain, obviously, that is separate from XRP.
- XRP are pre-mined. Ripple investors and team owned all 100B of them at the start. They can sell them off slowly, as long as there is enough demand at the current price they'll all be billionaires.
I think Ripple have two good things going, but buying XRP seems like too good a deal for them, not so much for the buyer.
It has a 60% premine that I will be using to attract people to the platform (lol).
So my current net worth is about $6T.