It never got off the ground because the basic idea is ridiculous - that everyone in the world should learn a new language from scratch.
English is (increasingly) the most widely-spoken language world-wide. It is the indigenous language of the British Isles, USA, Canada, Australia, New Zealand and large parts of the old Empire. It is spoken in Scandinavia and the Low Countries and is the favourite second language of most students. It is the international language of maritime navigation, air traffic control, computers and pop songs.
And so on...
So who needs Esperanto?