Thus we say: You never know, which is why but you never know. That is why and goes on to explain:

The grass is wet because it rained last night. This seems the simplest and most elegant expression of the meaning. I am always suspicious of reason (s) and why being next to each other. There can Ò€¦ Why is used here as an interjection. According to merriam-webster: €used to express mild surprise, hesitation, approval, disapproval, or impatience

Why is used here as an interjection. According to merriam-webster: €used to express mild surprise, hesitation, approval, disapproval, or impatience