Keep a few things in mind. Not all 80 billion XRP that OpenCoin is supposed to give away is already in people's hands. Also, the founders that kept 20 billion will probably not be likely to sell a big part of it. For this reason, the total amount of XRP in circulation is many times lower than 100 billion.
Beside that, it is true that the total market cap can be valued at 100 billion * 0.0044.. USD/XRP = ± 450 billion USD. But that number does not make too much sense because the price will drop very fast when people sell big numbers of XRP. The reason that the price has this (relatively high) value is because most people are not likely to sell their XRP and everyone wants to buy a little bit of them to experiment or to keep as an early investment.
The main reason why people buy XRP now is because they believe that Ripple has potential to become big some day. And possibly for development and testing purposes.
No, the -1 came from a troll who downvotes every ripple question. – o0'. – 2013-04-29T18:37:10.653
3That said, this is really not a great question, and way too much biased. – o0'. – 2013-04-29T18:39:22.537
1Why? What is the bias? I think it's perfectly normal to look for a logical explanation to this mind blowing number. – Emre Kenci – 2013-04-29T21:14:32.607
3"Ripple's a payment system that can't be used to buy anything yet" this is totally a rant. – o0'. – 2013-04-30T08:19:53.163
It is a fact. And it supports the question. – Emre Kenci – 2013-04-30T10:31:40.000
"Ripple's a payment system that can't be used to buy anything yet" is false, as for example here a Microsoft Surface RT was sold for 13k XRP. My interpretation is that you want to call attention to your concerns about Ripple, which as commendable as it may be is neither part of the question's topic, nor is SE the correct platform for that. – Murch – 2013-09-05T12:40:26.837