For the tl;dr crowd, it is not really an important question.
In expanded definition of what I think on existence, I will try to explain.
The question of my existence, or of existence in general, is really one which I don’t put much consideration into, mainly because I think it is a question which has relatively little importance.
To me, my ability to think, act, and experience is about as much I need for my own proof. If I am deceived by some greater being ala Descartes’ Evil Deceiver, then I must be some pretty big business to warrant that kind of attention. Cool, I guess. Whether what I am seeing is true or not, or my ability to perceive primary and secondary qualities, and whether they exist within me or within the object, I really don’t see an issue. For those qualities, it does not really change how I interact with the world. Take that, Locke and Berkeley. My philosophical education falls primarily into three or fourth different fields, if perhaps that offers some explanation to my attitude.
I am, first and formally, educated in an institution known for its focus on the History of Philosophy. Our curriculum is focused on delivering a well rounded view of the better part of three or four thousand years of philosophy. As a graduate institution, they also maintain tests on both the Masters and PhD level on the History of Philosophy. As I have been at the same institution for both my undergraduate career and my graduate career thus far, I have been fairly well steeped in the History of Philosophy.
The second major influence on my thought is the field of Hermeneutics, particularly cross-cultural hermeneutics. Hermeneutics is the field of interpretation, and in this case, it is taking the history and philosophy of each time period and taking into account the socio-political situation involved in each time period. It is an attempt to tease the most out of a thinker and field of philosophy without bringing too much of my own experience with it. Now, this is never 100% successful, but making the attempt yields a richer understanding of the thinker and their philosophy than if you view the philosophy of the past through a lens colored by your current philosophical thought. This also allows for better acquisition an application of philosophy without misrepresenting the thinker.
This follows along strongly with my secondary focus on philosophy, Asian Philosophy. Generally, I am more familiar with traditional Indian Philosophy. This included the Vedas, Jainism, Buddhism, the BVG and the Upanisads, and many of the Traditional Indian Schools like Nyaya, Vaisesika, Samkhya, Yoga, Advaita, and Vedanta. I have focused heavily on these because of my interest in non-Western thinkers and the radically different approach to philosophy. Furthermore, I have recently been strongly moving more towards East-Asian philosophy, particularly Confucianism, Mencian Confucianism, Daoism, Chan, and Mohism. I find these to be more accessible than many of the South-Asian schools, and are just as philosophically rich as their South-Asian counterparts.
My primary philosophical influence is from Classical American Pragmatism, particularly William James and Charles Peirce, though I have read and studied John Dewey as well. As far as philosophy goes, I generally self identify as a Pragmatist. Essays of particular note that should be read to get a better understanding on my thoughts here might be the series of essays (in this order) The Ethics of Belief by William Clifford, The Fixation of Belief by Charles Peirce, and The Will to Believe by William James. On that scale, Clifford’s essay is first, Peirce replies to him, and James replies to Peirce and Clifford. I side closest with William James, mainly because I am directly opposed to Clifford, and I don’t feel Peirce goes far enough. Furthermore, the essays “What Makes a Life Significant” and “On a Certain Blindness in Human Beings” by William James are also very influential on my thought. It would be an accurate statement to say I am a Pragmatist nee James.
I am far more concerned with the every day life, and find questions regarding the overall existence of humanity or myself in general to be questions which would have relatively little affect on how I go about conducting my life. While knowledge pertaining to the creation of the universe would surely be nice to have, my overall day to day existence would remain relatively unchanged; I am concerned with how to live while fulfilling whatever goals I have set for myself, and by following whatever highest ideal I have set for myself. Spending my time pondering question which do not have practical relevance to me is entertaining, but if I lose myself in pondering on whether I exist or not, I will surely miss out on the richness of life, or I will be too trouble to appreciate what beauty there might be in front on me. This part, I think, shows much of the Asian influence on my thought.
So, is existence important? Yes, only so far as I keep existing. Is my entire life one strait LSD trip? Who knows. But what I do know is that I can only live and react to the things I perceive, as I perceive them, and I mean this both intellectually and physically. I think it is a question of priority. If I am lost in trying to find God, I stand to miss out on seeing what good there really is in life.
And in the end, all I have right now is this life around me.