This is true, but why would somebody invest billions of dollars in bitcoins. All those billionaires out there didn't make money by being speculative. 
Plus, if you buy billions of dollars worth of bitcoins, liquidating it won't be easy.
Take a look at Warren Buffett ,he made his billion speculating. There are wise people who made billions through smart investments and holding those stocks for a longer time,i am not sure whether it is possible to invest billions of dollars through the exchanges we have right now,what ever may be the case i am positive that the price would rise later this year.Plus, if you buy billions of dollars worth of bitcoins, liquidating it won't be easy.