It is terribly hard to learn a foreign language – more so after you’re a grown up.
To address this problem, Esperanto was a language created in the late 1870s. It was started with a vision to make it the world’s universal second language for international communication. However, with only about 100,000 speakers today, it has fallen well short of that goal.
Esperanto has a highly regular grammar, and is one of the easiest languages to learn. It was specifically designed for a learner to be fluent in a few months. Yet, it hasn’t quite caught on. Clearly, the ease of learning a language wasn’t the bottleneck.
On the other hand, English has gained immense popularity in the last hundred years, and is the most widely spoken language in the world. The reason so many people learn English is not because it is easy to learn. English is a goulash of several Indo-European languages with idiosynchratic pronunciation and grammar that is about as regular as a hedgehog’s rear. Nevertheless, more people will continue to learn it and master it, merely because so many other people in the world use it. The rise of the internet has only accelerated this trend.
To make a language popular, you need a large community of people who already use that language. In this case, a popular language’s appeal would snowball at the cost of less popular tongues.
To start some movements, it is important to find out who else is on-board. Unless you have a large enough network, those movements are likely to fade away as soon as they begin.