You definitely can invest in USD/Euro. That is what people do on forex...
No, you don't invest in USD/EUR pair, you speculate. Forex trading is a zero sum game. My point is that Bitcoin does not reliably produce wealth, it is a currency, similar to speculating on forex. At some point, user numbers will reach saturation, and Bitcoin will no longer produce any returns (except maybe due to deflation).
are you really this fucking retarded?
YES you CAN and people DO invest in the USD/EURO etc. infact, people even make a living doing this.
here let me give you the retarded thread of the year award