In Japan, a well read feature in the newspaper used to be (I do not know current status -- it may be the same) to give the results of a survey of habits and methods. For example, do you brush the top teeth first or the bottom teeth first? Do you brush in a clockwise manner or a counter-clockwise manner or up and down? Do you wear socks to bed? Do you put your right sock on first or your left? Things like that.
A Japanese cousin came to the US with a friend in the 1980s and they had a guidebook -- a standard guidebook that most Japanese tourists used. It had a checklist for each tourist destination for them to check off as they did, or saw, an event. If they met another Japanese tourist, they would compare checklists.
Some cultures value the homogeneity of the group more than others -- but all have some degree of concern about "normal" behavior. This goal of conformity is not applied equally. In the UK, an unusual person of "upper class" is considered to be "eccentric" while working class people find the label of strange or crazy applied to them.
So, normal is primarily a matter of blending in -- when it matters what others think about you. In many countries, being rich means NOT caring about what others think about you. In class-stratified societies, that will apply to the higher level classes.
What is the value of being considered "normal"? Well, by definition, you are a part of a larger group who are more-or-less similar to you in thoughts and behavior and thus have a ready-made support group. If you are part of the primary "normal" group, then most people will be in that group and it will feel quite comfortable.
It is also quite possible to be part of a non-primary "normal" group. The primary group, once again by definition, will consider you to be "different", "crazy", "abnormal", possibly even "bad", but -- similar to the primary group -- you will also have a group of people more-or-less similar to you upon whom you can rely for support and verification.
Of course, this leaves the ones who are quite different and do not have any easily reached support group. But, within that scattered group of individuals they can still consider themselves to be "normal".
What about those who are truly aberrant -- defined by an agreement within the groups of professional psychologists -- who may not have any support for their behavior? As long as their behavior only affects themselves, there is no harm in considering them to be in their own individual group of "normal".
(It is a totally different thing if their behavior affects others or intrudes upon others' abilities to live their lives.)
