My point is that you can't satisfactorily gauge the Bitcoin risk at all (let alone set it to some specific value), since risk is a measure of deviation between annual returns of a financial instrument or investment, but you just don't have enough input to reach a conclusion that wouldn't be a wild guess. So how are going to accurately measure the risk of Bitcoin if it is only 6 years old and the majority of these years it languished in oblivion with its price next to nothing (yeah, I know it is painful to see)?
Risk is just measured by historical data. In future, any investment could be ruined to nothing. If you bought Russian government bond before 1998 and suddenly they defaulted, and many MBS/CDS etc... busted in financial crisis, they all looked good before the total collapse
Typically you don't want any data longer than 5 years to analysis, since market condition changes all the time, those old data are most irrelevant and misleading
The data itself may indeed be utterly misleading in the assessment of future risk (actually, any past data, for that matter), but its very existence is a factor that should be counted in. Gold being highly valued as long as humanity knows it has a lot of credibility in respect to its past performance (as a basis for forecasting its future performance). Bitcoin, on the other hand, having been "there" for just 2-3 years (I mean since it got out of total obscurity), doesn't have such basis, thereby any assessment of its future performance (based on past data) is fundamentally erroneous and bordering on sheer guesswork...