It's only self-evident if you're American and remember your history.

Abraham Lincoln was shot at a play, his wife Mary Todd Lincoln was sitting next to him.

The implication is to say 'even though your husband and President of The United States was just shot next to you, how was the play otherwise'

Meaning the recipient is being obtuse to the situation or is unaware of it.

I think what he is saying is that the avalanche is falling, and so it doesn't matter that some are left- they won't be for long.

Missing the forest for the trees.

Urban dictionary doesn’t even have the correct usage (and surely should not be your first point of reference). So please, try to add something substantive to _your_ response.