Note that you can cancel a transaction with replacing that with a new one paying higher fee only if the original transaction has been flagged as RBF.
Since almost all nodes are still using opt-in RBF and they have not enabled full RBF, if your transaction has not flagged as RBF, you can't replace it with a new one even if pay a very much high fee for the replacing transaction.

Of course, I am not saying you should accept an unconfirmed transaction, if it has not been flagged as RBF. There is no guarantee that an unconfirmed transaction will be finally confirmed.