Bitcoin has survived well so far and the experts believe it is not going anywhere so you don't need to worry about the wiping off stuff. There is a whole process of Ledgers known as the block chains to keep track of the Bitcoins out in the market. As far as the other crypto currencies are concerned, I don't really believe in their potential as a substitute to physical currency, the Kuwaiti Dinar is valued higher than the USD but forex traders don't invest in Dinars, they invest it USD because its widely accepted, same is the case with Bitcoin, it is the most widely accepted crypto currency and there is a finite amount of Bitcoin which makes it a far better investment than any other currency out there. The Pakistani Rupee has an 'intrinsic' value yet the government can produce a ridiculous amount of notes and manipulate the value of the currency, in fact the State bank occasionally drops the value of PKR on purpose so you might consider our local currency as "riba" influenced and go back to barter trade. There is no possibility of manipulating the value of Bitcoins unless someone invests heavily or sells a large chunk to cause a temporary fluctuation in the prices, so you should be more worried about hiba or Diba or jiba jiba jiba, because AFAIK Riba is related to interest rates or an imbalance in the value of traded items, not independent currencies.
