A: If we buy the apartment now, we would have to cut other living expenses and live less comfortably, perhaps in the next 10 years.

B: But if we don’t pull the trigger on this deal then we might never get the chance again. If the price continues rising, we would never be able to afford our own housing.

Note: This idiom means “to make a final decision or commit to a certain course of action.” Literally, pulling the trigger might kill someone, and as a metaphor, it implies the involved decision is a final and important one that’s hard to make.