I saw it pointed out somewhere that bitcoins are meant to be rare, and that once the final bitcoin is generated, as there's meant to be a set ammount, there will be many orders of magnitudes less of them than dollars, euros, or the etc. So, even if the cost right now is high, having a hash of them could become worth a great deal.
That is of course speculative, but when there's going to be 1 bitcoin for every 600,000 of today's dollars...assuming the sum of bitcoins becomes worth a thousandth of that of dollars, each bitcoin will be worth 600 dollars...run a mining op for one coin a day for a year(365 coins), hold onto it for a while, average the price down to 300 dollars a coin...sell for a hundred grand...
So running a bitcoin mining opp, or even buying the coins at current market value, is a feasible long term high risk investment. I wouldn't suggest putting all your eggs in that basket, but I would suggest adding the purchase of the occasional bitcoin (or the cost of mining) to your list of high risk investments.