The simulation argument:
The universe is made of mathematics. Human minds are ideas: that is, data. So the obvious question is, are we a simulation?
As humans we simulate other ideas. Not just with computers: even a hunter gatherer can dream, experimenting with new ideas that are not "real" but seem real at the time.
The universe is infinite, so these simulations could be infinitely complicated, because the person simulating us is even more complicated. Plus we can only think what the laws of our reality allow us to think. So we cannot tell from inside.
Since there are more simulations than "real" universes, and since we cannot tell which is which, it follows that we are more likely to be simulated than "real". And if we imagine worlds where every child has a computer containing simulated people, there could be billions of simulated worlds for every "real" world. So the idea that we are "real" is vanishingly small.
Of course, since time does not flow, and everything is made of numbers, and there are infinite levels of higher level intelligences watching every atom, all I have really described is the fractal nature of infinite reality.
In short, it's darned interesting out there.