Why do you think beatty let the first alarm ride in Fahrenheit 451?

Beatty may have let the first alarm ride in Fahrenheit 451 to test Montag's loyalty and commitment to their society's beliefs. By allowing things to escalate, Beatty could observe Montag's reactions and decide whether he needed to intervene or if Montag would self-correct his behavior. Additionally, Beatty may have been trying to provoke Montag into taking actions that would lead to his own downfall.