You are right. That number was in bitcoin's initial submission, which laid out the particularities and attributes of bitcoin under the pseudonym of Satoshi Nakamoto. We don't know who he is. It may also be a group.
This decision could be changed, but the consensus required to change that attribute is relatively improbable, since the vast majority of players in the bitcoin world behave in an economically rational manner. It would be irrational to devalue their assets. For example, by wanting to double the total quantity of bitcoins, bitcoin owners would devalue their currency for no reason. In fact, the real strength—