Or, Why I don't learn Chinese  (A long overdue revival of one of my favourite series on here!)
The Chinese are apt to boast of their language being the most widely spoken in the world.
After all, they say, there are 1.4 billion of us - what other language comes close to having that many speakers?
Well, in fact, of course, not even Chinese - putonghua, the official standardized form of the language, commonly known in the West as 'Mandarin' - comes close to having that many speakers. China's 55 recognised ethnic minorities (and various unrecognised minorities) each have their own - mostly quite unrelated - languages, and they account for some 10 percent of the population here. Even within the 'Chinese' languages spoken by the majority Han population, there are at least six major families of languages in addition to Mandarin, all pretty much mutually unintelligible.
The highest estimates for numbers of people who speak some Mandarin here are not much over 1 billion, and often as low as 700 or 800 million. And, in many cases, that's not going to be much more than a smattering - spoken garbled and grudgingly by people who regard it as a second language. And even amongst that large part of the Chinese population who are categorised as first-language Mandarin speakers (rather than speakers of Shanghainese [part of the Wu group of languages] and Cantonese [part of the Yue group] and so on) there are many accents/dialects that are barely intelligible to 'standard' Mandarin speakers: the people of Sichuan, for example, turn the tone system completely on its head!
People who speak a form of Mandarin that foreign students of the language might just about recognise, and speak it as their everyday language, are mainly confined to the handful of provinces in the northeast of the country, and number perhaps only a few hundred million. (Many foreign students find that even the accent and dialect of Beijing - which is supposed to be the foundation of standard Mandarin - is a bit of a challenge, and prefer to study further north-east, in Harbin or Shenyang, where the Mandarin they use is 'purer'.)
But, yes, even so, Mandarin does certainly boast the largest number of native speakers - by far - of any language in the world.
But the vast majority of them live in China. Until recently, the overseas Chinese diaspora were predominantly Cantonese or Hakka speakers. More Mandarin-speaking mainlanders are joining the exodus these days, but.... outside of a dense-packed overseas Chinese community, where are you going to hear Chinese spoken?
Is it an official language in any other country of the world? I think not. Malaysia would be the likeliest candidate, I would think - but NO; English, yes; Chinese, no. Ah, Singapore. But that's about it.
Is it an internationally used language in any field of business or academe? Apart from its inevitable recognition as one of the official languages of the United Nations.... I think not.
Mandarin Chinese, basically, is only spoken by Chinese people to other Chinese people - and almost exclusively within China. (And even here, they are starting to accept that they've got to learn to use English to communicate with the outside world.)
In an article (originally published in Language Today in Dec. 1997), The World's 10 Most Influential Languages, a Swiss linguistics enthusiast called George H. J. Weber made the argument that - based on a matrix of factors including the "socio-literary prestige" attaching to a language (another area where I suspect Chinese scored nul points) and the global standing of the countries that used it - English was by far the world's leading language. Admittedly, that was quite a long time ago now; but, as of 2008, Weber was confident that demographic shifts and so on had not had any significant impact on the basis of his ranking. Chinese came in at No. 6 - almost entirely due to its sheer volume of speaker population. English prevailed in the top spot - far, far ahead of French and Spanish in second and third places - primarily because it is spoken, to a significant degree, in well over 100 countries around the world. Chinese is never going to be able to match that.
I do find it difficult (impossible!) to justify making the effort to learn a language that only enables you to talk to the people of one country - even if there are an awful lot of them! Arabic or Spanish would be my top choices for another language. Or maybe Russian. (I already have a smattering of French and German.)