How Does Increasing Confirmation Requirements Mitigate Risk?

By increasing the required number of block confirmations for a deposit to be credited, the exchange forces a potential attacker to extend their malicious chain significantly longer than the honest chain. For a double-spend attack to succeed, the attacker would need to maintain 51% control and re-mine many blocks, which becomes exponentially harder with each confirmation.

This increases the cost and time of the attack, making it economically unfeasible.