As an atheist, I was seriously bothered by the thought of my inevitable, irreversible death in just a few decades. As a Friendly AItheist, I'm seriously bothered by the thought of highly probable astronomical waste, but cheered by the thought of MWI putting more of my future probability mass in universes that turn out really nifty, especially if I can help out with its creation. Of course, unless something like mangling takes place, MWI + quantum immortality is far more horrifying than astronomical waste.