Re "currency the whole world can use"
Nobody wants to own a currency, the spending power of which fluctuates 800% in a year, with an extremely narrow universe of people who accept that could ostensibly end in 5 minutes. That's worse than the bolivar. This is not "investing" anymore than trading pink sheet stocks of a bankrupt company is investing. You're gambling, speculating, in an asset that is readily and easily duplicated. It's not a commodity (eg, limited and finite natural resource).
The technology is great and absolutely has practical application. Currency is not it. eff, trading legitimate currency is one of the riskiest, most speculative, and complicates things even the most sophisticated "investor" can engage in.