In something of a chaotic stupor, the Moon tells me (among other things) to be nice to people because you can never know what they're going through, if you'll ever see them again- or if you're the last person they'll ever see. So, you may as well practice kindness with every being you meet no matter for how long.
You never quite know. You just might make someone's day. You just might save someone's life.
Worst case scenario, you're being nice, and that's not really so bad, after all.