I have a US silver dollar from 1884, made of silver. It contains more than a dollar worth of silver. Today's dollar coins are not made of silver. The "intrinsic" value of a silver dollar is about 27 grams of silver. That's what you can make into jewelry. You can trade in fractional BTC, so the quantity of BTC isn't a problem. Dollars remain in general use because they are relatively stable, reasonably secure, and have acceptable transaction costs. Those are the things that BTC lack. The desirable features of dollars all stem from the fact that the dollar is maintained by the US government. (Similarly for the major world currencies in general). BTC are an experiment in free market economics, to see what happens when you create a totally unregulated currency.