Considering the amazing amount of writing sites on the internet one would be tempted to think that poetry was immensely popular. The truth is though that in the 'real world' not many people actually do read poetry.
Part of the reason that people don't is that they don't grow up with it. Apart from certain types of children's literature (and the few awkward, sentimental and patriotic poems forced upon kids at school - with a few of the classics at subsequent, more posh schools) people don't get to see it much.
When they, unexpectedly, come upon true poetry, sometimes it can be a great hit. Elitist people love to sneer at the phenomenon but there was something heart-warming about the amount of books sold (and T-shirts and posters and what have you,) when that Auden poem was put to such dramatic and perhaps even perfect use in the movie 'Four Weddings and a Funeral.'
You remember the one, 'Funeral blues':
"Stop all the clocks, cut off the telephone,
Prevent the dog from barking with a juicy bone,
Silence the pianos and with muffled drum
Bring out the coffin, let the mourners come." Etcetera.
People who had never read or considered reading poetry suddenly 'got it' for a little while and were quite overwhelmed (for a bit) by what serious poetry could do to a person's system.
However, the bulk of all the poetry that ever gets written is of a certain 'age.' That is, it is a form of expression used by adolescents (and young adults) who are trying to find a way to quantify and qualify their feelings and reactions to the world at large and their place in it.
Most of the time, there's more emotion than craft here and as often, these people stop to write poetry when they become adults, with jobs, families etcetera. (It's even questionable how much poetry these people themselves read in their poetry writing phase.)
In short, there are only a very small number of people who make writing poetry a lifelong part of who and what they are. Few others will ever be exposed to it and most of the poetry out there is part of a coming-of-age tradition, which, if not actually giving poetry a bad name, does manage to 'hide' most other forms of poetry by its cheer bulk.
However, the fact that only a small percentage of the population reads poetry is not terribly important. It won't stop dedicated people from writing poetry. For these writers poetry is simply one way of looking at and digesting parts of the world around them: the ones visible and the ones hidden.
The writing of poems is also a very private matter. It is, in a way, very close to keeping a diary and as such it can be of personal and potential lifelong use to the writer, as well as a pleasure and a challenge to learn to do well.
In other words, for those who write poetry throughout their lives, readers are a bonus, not a prerequisite.
I esp. like the last sentence.
I think some "poets" also need to learn to leave their egos at the door.