albania

To answer the OP; because we assume we exist.

I believe the confusion and really the main issue is that this is totally the wrong question to ask. It carries a very simple but wholly important implication that goes unsaid. To ask why anything exists implies that something does exist.

There is no satisfactory proof that anything(we) exists. There are compelling reasons as to why we should assume anything(we) exists (in general these have to do with the futility of nihilism which is sort of the next logical step from believing nothing exists), but there is no unassailable proof of existence.

So let me pose this question: why are blimblams red? That in itself would be a confusing and unanswerable question because there is no answer to the more fundamental question : what are blimblams? If someone in the street asked me why does anything exist, I would respond with the appropriate question, do we exist?

Now, to go back to my first sentence. Suppose an object either has property A or does not have property A. Suppose further that indeterminacy in our system of reason implies that we can never know whether or not the object has property A. However, for compelling or even arbitrary whims we assume that the object does indeed have property A. Thus if anyone were to ask why does the object have property A, the obvious and logical answer is because we assumed the object had property A.

Edit: seems you beat me to it, refer to filtherton's post for a concise one sentence summation of what I meant