Is anything really that obvious ?

Many times, people use the sentence "Is'nt it obvious!", for many people. How obvious is it? Why is it so obvious? Is it really something that is so "obvious" that everyone in the world should know it? I don't know how correct am i, when i say there is nothing that is "obvious". Its a very relative term. Consider this very simple, but crude example. There are two people, both from the same strata of society. Both the people are pursuing history and are at the same level in thier graduate school. Not much difference between thier personalities. Now one fine Friday night, both go to play a game of Pool. Both are making merry and having fun. Consider now that it is person B's turn to hit the shot. He thinks that he can bank the ball and hit the stripe in. However person A feels, that he should not make that shot cause its an "obivous" possibility that he will miss. He thinks that B should hit the shot which is straight down. When he tells this to B, B replies saying that its "obvious" that he cnt make that long shot, because he cannot play a straight shot very well. He says he has a better chance, of potting a stripe, if he banks the ball. A retorts that, it is quite "obvious" that you will make that straight shot, as every beginner would know how to hit ball straight. Now here we see a classic example of what one thinks should be easy for everyone else, just cause the majority, not all mind you, find it easy. Is it correct to generalize so much? Just because 7 out of 10 have done it in the past, does it mean that even the next 3 will do it, to get a 100% result? It may be that certain people can do certain simple things better, while certain others find the same simple thing to be a tad complex. For instance i am good at visualizing 3-D geometry. So much so that i did not study for my Engineering Drawing class and still managed to get the highest score. However, many in my class felt the paper to be very difficult and did not do too well. Many designs, which to me seemed "obvious", weren't so for many of my colleagues. So whenever i would approach them with something "obvious", i would always have to eat my words, since i would land up explaining to them something that is "obvious" to me. Also, at this point, let me tell you, it is always hard to explain something that is "obvious" to you, to someone for whom it is not. This statement itself will corroborate the fact that anything "obvious" is not truly "obvious". It is relative. It may be "obvious" to you, simply because you may have been exposed to it in the past. For those who have not, it is'nt. For instance after reading this post, it is fairly "obvious" taht you will understand, indeed, that nothing is "obvious" .... or is it ?

Cheers