Perhaps from a different perspective; Everyone deserves and owns the right to...and pursuit of happiness. This isn't reserved for the few.
Just as depression isn't for everybody to feel. Although everyone will know sorrow. No-one is exempt from this. All part of this "blink" we call existence.
Yes some may "act" the part...or some may be just very optimistic.
But....like the old song "Smile" says; "If you smile thru your tears and sorrow...smile and may be tomorrow...you'll see the sun come shining thru for you." We can always strive for happiness...each and every day...each moment is a new opportunity for hope that this will pass. And...as annoying as "shiny happy people who wish to teach the world to sing in perfect harmony "are...God bless em! Cause...there...with the grace of God...go I also....someday!
Nothing jealous about that. Just have to keep trying each moment to attain it....grasp what is ours to "feel".
Take care....pray you find "yours".
m.b.