Express the reason or cause, often used to justify something.
Long explanation:
The ~だものだ grammar point is used to explain a reason or cause, often to justify a certain action, decision, or outcome. It is used in a subjective and explanatory tone, and can be translated as 'because' or 'since' in English. The formation varies depending on whether it is used with a verb, い-adjective, な-adjective, or noun.