[ijlx]

Well, for someone interested in languages conlanging can just be fun! I don't think most people are under the impression that their language will be popular.

It also serves as an interesting "what-if," i.e. what would a language look like if it were designed from the ground up to be as logical as possible. No idea if this is interesting to the average person, but it is to me.

However (and I'm not saying this is or will be the case with Ithkuil) there are several constructed languages that do indeed have sizeable communities (the internet has made this easier): esperanto, toki pona, lojban, even klingon has multiple speakers.