I sat in a Xtian service last Sunday where selfishness, egoism, et cetera were denounced, but then we sang praise to God because God Can Save US.
There's no escaping one is a self and that self is as deserving of one's love and care as your ailing grandmother.
There's a special value to taking extra good care of yourself: assuming you're not a sociopath and have healthy empathy levels, you will be more inclined to make lifestyle changes that reduce harm on other beings, because we feel pain knowing that Chinese factory (or Amazon!) workers labor in conditions we feel are more slavery than not, or that factory livestock animals endure torture so that we can buy more flesh for less. (Imagine a meat dept that promoted a sale that way: FLESH FOR LESS!)
If we care enough about ourselves to desire happiness enough to strive for it as an attainable goal, we find new motivation to make that vegetarian crossover to a meatless diet. Rather than deem it a futile gesture that won't really make a difference in the big scheme of carnivorous things, one says, 'But I will be happier if I abstain from subsidizing the factory meat industry. I will enjoy looking in the mirror of my conscience rather than loathing what I see.'
Taking care of ourselves is not mutually exclusive of being our sister's keeper. Just as the wiser sociopaths learn to care about the effects of their actions on others so that they don't experience retribution for the harm their apathy causes others, so they aren't exiled from their circle of friends and have no one to call on when they seriously need help, so do the wiser empaths learn to nurture themselves exquisitely, because it is Hard Work caring about one's fellow beings.
But, to quote the song: