@blueveinedthrobber,
So the universe is god's garage?
The question 'why does the universe exist' is akin to the questions 'what is outside the edge of the universe' and 'what was it like before the beginning of the universe'.
"Why" requires a context.
"Why did you reach for the glass of water?"
"Because I was thirsty"
"Why does iron rust?"
"Because molecules in iron binds with molecules in air, which creates rust, or iron oxide."
In each case the answers to 'why' depend on a greater context. Thirst - water - no thirst. That is the 'why' of the glass of water. Iron - air - they mix. That's the 'why' of iron rusting.
In the case of the universe we don't have such chains of reasoning. (we don't know) - universe - (we don't know).
It is possible to say and think "I will lock the drawer and then put the key in it". But that doesn't mean that it is a sensible thing to say and think. The question of this thread is similar.