a) You'll note I said "immediately" - Bitcoin is volatile, but rarely that volatile
b) The same applies to other currencies. If you want to call those "scams", then I'll simply admit we have a different definition of that word.
c) I still don't see the scam. Who's benefiting? Bitcoin's value feels market-driven. "Scam" implies there's some puppeteer jerking the strings in order to make a profit.
Whether or not BTC will hold its value in the long term, I see no way to interpret it as a scam.