Fate.

Telling someone not to be sad because someone else is going through more crap than they are is ridiculous.
It's like telling someone not to be happy because someone out there has better things and a genuinely better life than theirs.
People are so stereotypical, that they sometimes don't even realize that they are hurting others' feelings.
Like, I've heard so many people justifying that, no, just because someone did something bad, they aren't bad people.
You know what? I disagree.
Yes, bad things happened to them, so they did something bad.
But, you know what? Bad things happen to everyone.
Tragedy strikes everyone, not looking at whether they're old or young, or innocent or not.
Everyone is equal in the eyes of life and death, right?

Yes, bad things happen to everyone.
Now, see, that's when you find out who's naughty and who's nice.

Why, I know so many, literally SO MANY people that have been through shit, and yet they're the nicest people I know.

Bad things happen to everyone. Everyone cries the same tears and endures the same pain.
These tragedies are what make the bad people do bad things.
They're also what make the good people, good.

It depends on you, entirely.
It's all in your hands.
"It is the fool and the coward who says- "This is fate", so says the Sanskrit proverb. 
It is the strong man who stands up and says "I will make my fate"."

Ps.- Yes, okay I quoted Swami Vivekananda. So sue me.