0 Well, part of the reason it's considered to be the "most spoken language", is because of nationalistic reasons. Most varieties of the Sino-Tibetan language family are all called "Chinese", but that doesn't make them have any more claim to be the same language, because some varieties are more different than some European "languages". So, if for some reason Western Europe was conquered and mad
Also, we need to consider compulsory language education. In theory, Chinese children, no matter their first language, are to learn Putonghua starting from the age of six (as per what I am told by some mainland peers), with the two newly returned regions (Hong Kong and Macau) being an exception.