"Are you seeking great things for yourself? Do not seek them." -Jeremiah 45:5

"Birds of a feather flock together." -common proverb

"Don't say I didn't warn you." -Taylor Swift

The best argument against acting purely out of your own self-interest is simple; if that's who you choose to be, then you'll invariably be drawn to other people who share this characteristic. And ultimately, those people are not going to care about you.