What risk? All the Bitcoin miners I know are patting each other on the back on how much mining their fancy GPU is doing. Risk: one or more graphics cards (that are also used to play videogames) and a slightly elevated electricity bill from leaving the computer on all day and night. There isn't a lot of effort or ingenuity going on here, just an information asymmetry.
There's exchange risk as with any currency. If you exchange US dollars for Mexican pesos, there's a risk that the pesos will lose value relative to the dollar. Of course, the risk of keeping bitcoins is much higher than that of Mexican pesos.
By the way, you seem misinformed about the way people are mining bitcoins. Nowadays it's done mostly by professionals running rigs with tons of GPUs, not by individuals who put an extra graphic card on their gaming PCs.
