ㄴ다니까요

I am telling you, politely

It repeats a claim because the listener seems unconvinced, or simply to underline it: food really does make people happy, we will end up seeing each other again, it always happens. It is insistent but friendly rather than sharp, and it often lands at the end of an anecdote as the punchline. Drop the 요 and you get the blunter 다니까.

Register: polite, emphatic conversation