There's a 500 year old law that explains why nobody spends Bitcoin.
Gresham's law says people spend what they trust least and hoard what they trust most, which is roughly how gold and silver divided the work between them for centuries.
Something similar is happening now, though not for the reason Gresham described.
- Bitcoin barely circulates because people plan to hold it for years, which reflects their time horizon more than the money itself.
- Litecoin circulates because it was built to, with none of its design assuming you were ever going to sit on it.
The difference between those two positions is that hoarding is a bet on what happens later, whereas circulation is something you can observe happening now, and it is considerably harder to manufacture.
Payments. Privacy. Hard money