why can't everybody be happy?

The happiness of each individual varies in his/her mind expectations and how she/he deals with happiness,sometimes happiness is hard to feel/find if you are saying life is unfair, and so they will never be pleased of anything they achieved and end up like disappointed about life brings to them.They are not satisfied of what they have and what they achieved.If they know how to deal with life, they will realized LIFE is full of happiness !

To become happy or not.. it's totally depends upon you. if you think night is good we can sleep and get energy for new work.. you will be happy at night.. if you think we can't watch TV for late night. can't play outdoor games :-) we will be sad. all depends upon our thought..

Because we all have different behavior and attitudes, different views on things, and we're not in the same situation. We all have different level of appreciation on things around us. Don't worry too much... Have a nice day!