They can be created for different reasons.
Esperanto is the most successful conlang, counting on two million speakers worldwide and was created to render the study of a foreign language easier.
Some languages, though, can be created to represent communication in fictional realities, such as Klingon (Star Wars), Elvish (Lord of the Rings) and High Valeryan (Game of Thrones).
Those can still be learned and Duolingo has even launched a Klingon course for English speakers.
Are you studying or do you intend to study a conlang?
Does it help you somehow with other languages (or the other way round)?
Can you communicate with other people in that language?
Thanks for your comment.
I can’t picture myself doing it either.
I usually learn a language because I want to have contact with different cultures (read their books, know their music) and to communicate with more people.
That’s just how it works for me.
Then I see some people who learn Klingon, Elvish…. I would like to understand it better.
Apparently italki’s community isn’t really into those languages though haha
I never would seriously study a constructed language (just give it a look for curiosity).
There are enough real languages to choose from.
It seems to me that Esperanto had in the past some success among people living under communist regimes, because it gave them a good opportunity to travel officially and go abroad to language meetings. One of my first Spanish teachers was Cuban and he spoke Esperanto fluently.