The other big reason for caring is the "Doomsday argument" and the fact that all attempts to refute it have so far failed.
Jaan Tallinn's attempt: Why Now? A Quest in Metaphysics. The "Doomsday argument" is far from certain.
Given the (observed) information that you are a 21st century human, the argument predicts that there will be a limited number of those. Well, that hardly seems news - our descendants will evolve into something different soon enough. That's not much of a "Doomsday".
I described some problems with Tallinn's attempt here - under that analysis, we ought to find ourselves a fraction of a second pre-singularity, rather than years or decades pre-singularity.
Also, any analysis which predicts we are in a simulation runs into its own version of doomsday: unless there are strictly infinite computational resources, our own simulation is very likely to come to an end before we get to run simulations ourselves. (Think of simulations and sims-within-sims as like a branching tree; in a finite tree, almost all civilizations will be in one of the leaves, since they greatly outnumber the interior nodes.)
r/Fitness does a weekly "Moronic Monday", a judgment-free thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. I thought this seemed like a useful thing to have here - after all, the concepts discussed on LessWrong are probably at least a little harder to grasp than those of weightlifting. Plus, I have a few stupid questions of my own, so it doesn't seem unreasonable that other people might as well.