we exist because the alternative, that nothing exists, is not possible. We are living in a reality that is trying to find the best way for itself to exist, since it knows that it must exist, just like energy can neither be created nor destroyed.

A universe or reality without life cannot exist because there would be nothing in that universe that knows it exists. Life is inevitable: if all life in the universe were to die the reality would cease to exist. But that is not possible.

If you can get your head around the notion that time is an illusion, that time exists because that is how we observe reality, then there was never a 'time' when we, the conscious observer, were not 'here'.

"Why does life on Earth exist?" Why do people go on rollercoasters? For the fun of it, they don't do it to get to the other end, it is for the experience, the thrill of it.

"And what happens when we die?" Reality may have many forms. Why do we think there is only the reality we inhabit? There might be realities where there is no time or dimensions, no matter, only thought. Or realties where time is backwards, or more dimensions, or realities which we are unable to comprehend because there are things that don't exist in our universe.

The purpose of life is simply to live. That might seem silly but really, why is it any more complicated than that?