[benj111]

I picked on bitcoin because there will only ever be a limited number of coins, I could just have easily picked on gold. This is in contrast to the USD, where more can be printed bringing about inflation.

Money that "does something" ie gets lent to businesses to expand, or to people to buy houses is being allocated, its being allocated to something productive, whereas under the mattress isn't. Under the mattress isn't economic activity, lending it out is, or can encourage it at least.