Money has multiple functions, one of them is hoarding (aka saving). Even if Bitcoin had zero merchants and served this hoarding function alone it would be valuable.
Because it is:
- Decentralised
- Non-inflationary
- Easily stored and transferred
- Anonymous (sort of)
- you continue...
I would argue that in a conventional economy there is a difference between hoarding and saving.
Saving = Investment, ie savings are productively invested in the future of the economy
Hoarding = burying in the back garden (or location of choice) - this is a non-productive use of resources - and there are very few ways currently of productively investing BTC (I am not sure lending them on margin counts - and Havelock Investments and the like are not yet trusted by large sections of the community - with many valid reasons)