Is it because Gold has a much bigger market cap than bitcoin meaning it cant be manipulated by a whale pumping gold price like 10% in a day?
Bitcoin's 10% a day is not done solely by a whale. Or at least I don't think so, not at current prices and volumes. But it is related to the fact the market is not properly regulated and:
* whales can manipulate it. Not at 10%, but still.
* inside trading may be more a rule than an exception
* huge margin trading is allowed
* many traders are too young/inexperienced
All these
can have a cascading effect of whatever the whale does. It's not guaranteed though.
It's not that gold price cannot be manipulated. But the potential effects are not that big.