Why do people post 'first'?

I’m sure that all of you, before you found your way to the safe haven of Fluther, have encountered the phenomenon of the ‘first’ poster. In its simplest form, the first person to post a comment on a video or similar will simply post some variant on “first!111!1!1!!”, barely able to contain their excitement at their monumental achievement. If the thread is a popular one, and lacks the live refresh feature sported by Fluther, this can go on for pages, followed by people making fun of the ‘first’ posters, people posting “second”, people making fun of the ‘second’ posters…It hardly seems worth it really. So, why do they do it? Do they imagine that, secretly, everyone is envious of their greatness? And you, can you say in all honesty that you would not be tempted in their place to post that little word of celebration? Or, perhaps, you really are a closet ‘first’ poster. If so, you have some explaining to do.