This may be felt by non-L1 English speakers to be a somewhat dubious point, but for the L1 speaker it is far more difficult to acquire a working knowledge of other languages than it is for speakers of other languages to acquire at least some English: wherever the mother tongue English speaker goes, the probability is that people will have a better command of English than s/he will of the local language. Consequently, communication is more likely to take place in English than in the other language in question. The success of English has a price-tag for English speakers too: the greater likelihood of monolingualism and its attendant cultural myopia.