I have no idea what happens when we die.
I mean that not in the physical sense, of course, since it's pretty obvious that our skin and bones and meat get churned up into the earthly soup, one more ingredient in the food chain.
The question of whether we have a soul or mind or self or whatever you want to call it is unanswerable, so too is the question of what happens to it when we cease to exist inside a body. I haven't seen anyone come back from the dead, and the few reports of this happening are either religious in nature (and thus a matter of faith, regardless of your take on that), or in questionable circumstances. I've never seen someone get squished by a truck, for example, and then immediately pop right back up again and exclaim, "I'm fine! Don't worry about death, it's cool, I've been there!"
It just seems a waste that we spend our entire lives caring about ourselves and our family's selves, and our friends' selves, and then have them mean absolutely nothing in the grand scheme of a multi-billion year universe.
Granted, we only live in the here and now, so attempting to perceive the expanses of an infinite existence (apart from a physical universe), is an exercise in arrogance. How so? Because only an omniscient being can know everything, and since I am not omniscient (at least as far as I know), I am presupposing that I can even understand everything in the universe, let alone anything on a macro scale. And by macro I mean what is beyond this universe, and what is beyond that, and so on.
Regardless, however you look at it, death sucks.