many people here seem to be telling me that's impossible without some sort of cognitive dissonance

"People here" are not perfectly rational and prone to other-optimizing. Including yours truly. Even the fearless leader has a few gaping holes in his rationality, and he's done pretty well. I don't know which of his and others' ideas speak to you the most, but apparently some do, so why not enjoy them. If anything, the spirit of altruism and care for others, so prominent on this forum, seems to fit well with Mormon practice, as far as I know.