Why would anything need to exist, without something to witness it's existence?

This is a very skewed and ego-centric view. Saturn doesn't need rings, and it especially doesn't need them for the pleasure of others viewing, Saturn just has rings. Things are as they are.. and who is to say they are meaningless unless witnessed?

Flowers are different colors to attract pollinators, they are as they are because that is how they needed to be to survive.

Humans have only been around for a very short time in earth's history. There is much we have not witnessed, that does not make it any less worthy, or meaningful.

Life is not made for the pleasure of viewing, life is made to survive and adapt. Sometimes this results in beautiful things, sometimes this results in terribly ugly things.. but the worth of life goes far beyond mere appearance.

The Over Inflated ever so Self Important Aggrandizing Pompous Ego of Man speaks...

if we are not around to witness something why should it bother to exist?

Things exist quite well and are much better off without us around to witness such. Humans are quite a new concept in the grand scheme of the Universe. It has done ever so magnificently before we got here.

Well I would answer that the things that the 'witness' was made of needed to exist before the witness could contemplate existence. So yes.

Good question. It would be stupid, wouldn't it, to have something and no one to witness it. So who or what is that something? That is the greatest mystery of life, I guess. I also guess that it is who and I, the real you and I, who are the witnesses. The only problem is that we have become so deeply entangled in the material world, the world of maya, of delusions, that we have forgotten our true identity. We started off as spiritual beings having a human experience but ended up as human beings having a spiritual experience. Well, I guess you are on the right track. Now you got to take that adventure and find the answer for yourself. Who is that silent witness?

Nature gives all things not made by man its purpose. Nature does not need anyone or anything to witness it. From the very moment of the Big Bang and everything that happened before it, nature existed without life to see it.

"Epistemological objectivity" [Montague] states that all existents exist independently of our consciousness of it. That which exists independently of consciousness and is not itself conscious, has no awareness of its own existence.

Why would anything need to exist in the first place. Open question

The need is experience. Witness is not necessary.

Life and existence are their own raison d`aitre

To truly believe otherwise is possibly a hubris

arising possibly,from semantic linear thinking.

Excellent "observation".

Because it lacks objectivity, and also does not actually need it.