No one should expect to be happy. Happiness is not guaranteed.

I agree that happiness is not guaranteed, but also think everyone deserves it, even if they don’t get it. Small distinction, but to imply that someone perhaps suffering from depression or stuck in really terrible circumstances doesn’t even deserve happiness sounds very harsh.

Why does everyone deserve happiness? That's nonsense. There are some really horrible people out there who refuse to change.

'God Almighty himself is under the necessity of being happy; and the more any thinking being is under that necessity, the nearer it comes to infinite perfection and happiness.'

There are also people who can only be happy at the expense of others

It's reality

"Deserves" is a "should"-level concept, not an "is"-level concept. "It's reality" is not an answer to why someone does or does not deserve something.