Why do people have different "happiness"?

If happiness is something internally normal (typical) for humans, why is it filled with different meaning for and achieved differently by different people? Why are some people happy because they are in strong health, others because they have a beloved one beside them, for still others because they love how they are spending their life in general? Is happiness something that is related only to our inner world ("be happy with oneself") or is something in the outside circumstances (money, love, sense of belonging, etc)? When people say they are happy, are they happy with what they have or with what they are? Does the feeling of happiness depend anyhow on the people's upbrining, education, world outlook, status in the society? ("the less you know, the better you sleep",i.e.happier?)

Why do people behave like this on board a plane?

Why do people carry big and heavy suitcases on board with them if they cannot lift these by themselves (or even carry sometimes) and ask the cabin crew to put it in the overhead stowage (not even "help" but "do" it)?
Why do people - having a headset on - shout when talking to cabin crew? (who is basically in the headset and cannot hear - the cabin crew or the passenger?)
Why do people need to stop a passing-by cabin crew and request something if they see that the cabin crew is walking pretty quickly,almost rushing, to get something for the service process?
Why do people think that if they have bought a ticket for the flight, they can behave as gods, believing that the price of the ticket also included the whole aircraft, pilots, cabin crew, etc.?
Why do people complaint that nobody has attended to their call bell for "ages" if they see that all the cabin crew are busy in the cabin?
Why do people close the windows in the toilets at the altitude of 12km, whether it is a day or night?
Why do people travelling with infants expect the airline to have litres of milk, baby meals or even diapers, as if there were a shop on board?
Why do people stand up and grab their luggage to go when the aircraft has hardly touched the ground?
etc. etc. etc

Why do (not) people believe in extraterrestrial life?

Why do some people like to talk about UFOs, giving vivid examples of their visits to the Earth, while other people donot believe that somebody "out there" might be interested in the human civilization? Was the Life on the Earth brought from far away in space by Somebody/Something or did it evolve in the normal course of time, without any interference from outside? Do "aliens" really visit our planet (and allegedly abduct people for experiments) or is it only the people's sick imagination? Why are aliens always pictured with humanlike features (with legs & hands, eyes, etc) and not something that is really unique and cannot be compared to anything on the Earth? If the "truth is out there", when will people be able to discover it?

Why do people believe in superstitions?

Why do people believe in things that are basically irrational, not even based on any experience or reason? Why would two persons shaking hands across the gate bring on themselves ill luck? Why will the bride cry all her married life if it rains on the wedding? Why will you have good luck through the year if you find money and keep? Why will two persons quarrel if they, while walking, divide so as to pass an obstruction one on one side and one on the other? Why would the nose itching foretell company: If on the right side, it means a man; if on the left, a woman? etc,etc,etc.

Why do people fear?

Why are some people afraid of flying? using a lift? being in closed or open/crowded space, fast driving, hospitals, spiders, etc, etc, etc, even if they have not had any negative experience before? Why don't other people fear the same things? What makes our mind resist this and forces us to experience such a negative feeeling?