Bitcoin is a hard and decentralized money.
A hard money provides the function of having constant savings. Thus, it is between a fiat money and an investment:
  • A fiat money is stable but declines in value
  • A hard money is stable and is constant in value
  • An investment is volatile but goes up in value
It's sandwiched in between. The less volatile markets become, the more surplus budget money to invest people have the less there is a need for savings.