Silver is a primarily a working metal, bitcoin is primarily a speculative currency.
As long as it's not hacked, bitcoin will go up as it is limited. Where as silver or gold will not run out ie infinite supply in our life time. If silver become, $50, $100, $200 an ounce, many mines that was closed as uneconomical will open up making more silver available.
The thing I worry about bitcoin is that it is one hack away and people will lose confidence and being a virtual currency it has virtually nothing backing it.
Having said that few dollars I spent ten years ago, is now a significant sum.