We usually want to help people who make us feel good. Even if the person already has way more than they need.
But someone who makes us feel bad is hard to love. Even if they’re merely expressing frustration over their suffering.
That’s usually why we treat people badly. Because the person contributed to our suffering in some way. Or at least we perceive that they did. In some cases, we’re merely doing it to ourselves.
If we’re able to see that the other person is acting the way they are because of their suffering, we can avoid being angry with them and avoid adding to our own suffering.