I think that the billionaires do invest in bitcoins . Bitcoins has such huge market value and popularity , there is no way that they have not invested in bitcoins. If they don't invest bitcoins publicly , they invest in it privately . They prefer to remain silent.The billionaires has a lot of money , they can easily invest and profit out of it .
I am very much sure most of the billionaires must be aware of existences of such a new currency system and its potential too.