Why do people get stressed at work?

Why do some people get stressed at work while others remain calm by doing the same job? Does it have to do with the level of self-confidence or experience? Is this stress the result of fear to fail, when such people feel a great (personal/internal) responsibility for doing the task in the proper way? Don't others ("calm" people) then feel responsibility in the the same way/level as the "stressed" people? Or is it simply in the character, to worry for fulfilling any task properly, even though they might understand that there's nothing to worry about?

Why is homosexuality popular?

Why would a guy be expected to be gay if he doesn't have a girl friend, but very few would expect a girl to be lesbian if she doesn't have a boy friend? Why would people think quicker of male than female homosexuality? Why do people talk about gays more than lesbians? Is it so normal for girls to be depicted as lesbian because of their "female" nature (when girls holding hands will be quicker considered as just friends rather than partners)? Why would people rather believe that a single guy is gay than just unlucky with finding a girl friend? Why has male homosexuality become so widely spread, even in societies that originally banned (or still ban) it legally (at least officially)?

Why is it (not) easy for people to decide what they want in life?

Why can some people steadily reach their goals in life, one after another, as if they were born with these goals (like a train moving confidently on the rail track), while others "float" trying to understand what they want (like a boat on a lake)? Why do some people know what they want to be/have in life and others don't? Does it by any chance depend on the upbrining? education (knowledge)? social environment? character?
Which one is better to be - "the train" (going on the rails firmly but with a risk of running off the track in case of a single error) or "the boat" (enjoying the flow but risking to fail in reaching the shore)? Should we feel sorry for the former or the latter?
Generally, do people have to know what they want to reach (have/be) in life?

Why do (not) people marry?

Why do some people marry and some remain single for a long time? When the latter say "afraid of losing their freedom", what do they mean by "freedom"? or do they fear that the relationship in marriage will somehow be worse than just dating/cohabiting? why are they not afraid of staying alone (though still dating from time to time) till their last day? or are they (but still cannot make the right step because of the fear of hearing "No")? Or do they think that living alone is better than having a partner, even when most people in the world prefer to have a partner? (as proved in "Why do people need a partner?")(being afraid of losing their beloved one one day who has been the sense of their life). Or, after all, is it something about them makes other people not want to marry them (too self-centered, not trustworthy, too dominant or too weak)?

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?