That’s not exactly true, that nobody speaks it. There are a couple of hindrances to speaking it, basically finding the people willing to be occupying that niche and then those who actually want to learn and speak it to a high degree.

They are equally useful and about as well developed.

Comparing Esperanto with Klingon is comparing apples and oranges. No, Klingon is not that developed as Esperanto is. Klingon is for a bunch of enthusiastic Trekkies who wan’t to live their universe. Esperanto has a 136 year old history with a bunch of literature, music and tradition behind it.

No other constructed language has that.

Nobody uses it. You’ll be the only one.

What for a pile of crap of an opinion. Most languages can be described as “nobody” uses it. When you are outside of the top 10 languages in the world, then any language is a harder way to use it. You could move to the country or region where it’s then spoken or maybe find the community in your city which speaks such a language.

Esperanto can be also found like that. There are people who speak it and also there are regular events where people can meet up.